Publications

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the signal peptide-like segment of hpaxm is required for its association to the cell wall in transgenic tobacco plants.harpins, encoded by hrp (hypersensitive response and pathogenicity) genes of gram-negative plant pathogens, are elicitors of hypersensitive response (hr). hpaxm is a novel harpin-like protein described from cotton leaf blight bacteria, xanthomonas citri subsp. malvacearum-a synonym of x. campestris pv. malvacearum (smith 1901-1978). a putative signal peptide (1-mnslntqiganssfl-15) of hpaxm was predicted in the nitroxyl-terminal (n-terminal)by signalp (signalp 3.0 server). here, we explored the f ...201728141855
engineering canker-resistant plants through crispr/cas9-targeted editing of the susceptibility gene cslob1 promoter in citrus.citrus canker, caused by xanthomonas citri subsp. citri (xcc), is severely damaging to the global citrus industry. targeted editing of host disease-susceptibility genes represents an interesting and potentially durable alternative in plant breeding for resistance. here, we report improvement of citrus canker resistance through crispr/cas9-targeted modification of the susceptibility gene cslob1 promoter in citrus. wanjincheng orange (citrus sinensis osbeck) harbors at least three copies of the cs ...201728371200
protein depletion using the arabinose promoter in xanthomonas citri subsp. citri.xanthomonas citri subsp. citri (x. citri) is a plant pathogen and the etiological agent of citrus canker, a severe disease that affects all the commercially important citrus varieties, and has worldwide distribution. citrus canker cannot be healed, and the best method known to control the spread of x. citri in the orchards is the eradication of symptomatic and asymptomatic plants in the field. however, in the state of são paulo, brazil, the main orange producing area in the world, control is evo ...201728343961
complete genome sequences of six copper-resistant xanthomonas citri pv. citri strains causing asiatic citrus canker, obtained using long-read technology.the gammaproteobacterium xanthomonas citri pv. citri causes asiatic citrus canker. pathotype a strains have a broad host range, which includes most commercial citrus species, and they cause important economic losses worldwide. control often relies on frequent copper sprays. we present here the complete genomes of six x. citri pv. citri copper-resistant strains.201728336584
ecological and evolutionary insights into pathovar diversity of xanthomonas citri.citrus canker, caused by xanthomonas citri pv. citri (xct), is a serious disease of citrus plants worldwide. earlier phylogenetic studies using housekeeping genes revealed that xct is related to many other pathovars, which can be collectively referred as xanthomonas citri pathovars (xcps). in the present study, we report the genome sequence of eighteen xcps compared with four xcps available in the public domain. in a tree based on phylogenomic marker genes, all the xcps form a monophyletic clust ...201728258140
xanthomonas citri pv. citri pathotypes: lps structure and function as microbe-associated molecular patterns.xanthomonas citri pv. citri is the pathogen responsible for asiatic citrus canker, one of the most serious citrus diseases worldwide. the lipopolysaccharide (lps) molecule has been demonstrated to be involved in x. citri pv. citri virulence. despite enormous progress in investigations of the molecular mechanisms for bacterial pathogenicity, determination of the detailed lps structure-activity relationship is limited, as the current knowledge is mainly based on structural determination of one x.  ...201728186388
selection of small synthetic antimicrobial peptides inhibiting xanthomonas citri subsp. citri causing citrus canker.citrus canker disease decreases the fruit quality and yield significantly, furthermore, emerging of streptomycin-resistant pathogens threatens the citrus industry seriously because of a lack of proper control agents. small synthetic antimicrobial peptides (amps) could be a promising alternative. fourteen hexapeptides were selected by using positional scanning of synthetic peptide combinatorial libraries. each hexapeptide showed different antimicrobial spectrum against bacillus, pseudomonas, xant ...201728167892
ectopic accumulation of linalool confers resistance to xanthomonas citri subsp. citri in transgenic sweet orange plants.in order to clarify whether high linalool content in citrus leaves alone induces strong field resistance to citrus canker caused by xanthomonas citri subsp. citri (xcc), and to assess whether this trait can be transferred to a citrus type highly sensitive to the bacterium, transgenic 'hamlin' sweet orange (citrus sinensis l. osbeck) plants over-expressing a linalool synthase gene (custs3-1) were generated. transgenic lines (lil) with the highest linalool content showed strong resistance to citru ...201728131994
adaptation of genetically monomorphic bacteria: evolution of copper resistance through multiple horizontal gene transfers of complex and versatile mobile genetic elements.copper-based antimicrobial compounds are widely used to control plant bacterial pathogens. pathogens have adapted in response to this selective pressure. xanthomonas citri pv. citri, a major citrus pathogen causing asiatic citrus canker, was first reported to carry plasmid-encoded copper resistance in argentina. this phenotype was conferred by the coplab gene system. the emergence of resistant strains has since been reported in réunion and martinique. using microsatellite-based genotyping and co ...201728101896
pseudomonas protegens cs1 from the lemon phyllosphere as a candidate for citrus canker biocontrol agent.citrus canker is a worldwide-distributed disease caused by xanthomonas citri subsp. citri. one of the most used strategies to control the disease is centred on copper-based compounds that cause environmental problems. therefore, it is of interest to develop new strategies to manage the disease. previously, we reported the ability of the siderophore pyochelin, produced by the opportunistic human pathogen pseudomonas aeruginosa, to inhibit in vitro several bacterial species, including x. citri sub ...201728194866
the arabidopsis elongator complex is required for nonhost resistance against the bacterial pathogens xanthomonas citri subsp. citri and pseudomonas syringae pv. phaseolicola nps3121.although in recent years nonhost resistance has attracted considerable attention for its broad spectrum and durability, the genetic and mechanistic components of nonhost resistance have not been fully understood. we used molecular and histochemical approaches including quantitative pcr, chromatin immunoprecipitation, and 3,3'-diaminobenzidine and aniline blue staining. the evolutionarily conserved histone acetyltransferase complex elongator was identified as a major component of nonhost resistan ...201728134437
inducible expression of bs2 r gene from capsicum chacoense in sweet orange (citrus sinensis l. osbeck) confers enhanced resistance to citrus canker disease.transgenic expression of the pepper bs2 gene confers resistance to xanthomonas campestris pv. vesicatoria (xcv) pathogenic strains which contain the avrbs2 avirulence gene in susceptible pepper and tomato varieties. the avrbs2 gene is highly conserved among members of the xanthomonas genus, and the avrbs2 of xcv shares 96% homology with the avrbs2 of xanthomonas citri subsp. citri (xcc), the causal agent of citrus canker disease. a previous study showed that the transient expression of pepper bs ...201728155188
complete nucleotide sequence of a new filamentous phage, xf109, which integrates its genome into the chromosomal dna of xanthomonas oryzae.unlike ff-like coliphages, certain filamentous inoviridae phages integrate their genomes into the host chromosome and enter a prophage state in their infectious cycle. this lysogenic life cycle was first reported for xanthomonas citri cf phage. however, except for the x. citri phages cf and xacf1, complete genome sequence information about lysogenic xanthomonas phages is not available to date. a proviral sequence of xf109 phage was identified in the genome of xanthomonas oryzae, the rice bacteri ...201727743252
xanthomonas citri subsp. citri surface proteome by 2d-dige: ferric enterobactin receptor and other outer membrane proteins potentially involved in citric host interaction.xanthomonas citri subsp. citri (xac) is the causative agent of citrus canker, a disease of great economic impact around the world. understanding the role of proteins on xac cellular surface can provide new insights on pathogen-plant interaction. surface proteome was performed in xac grown in vivo (infectious) and in vitro (non-infectious) conditions, by labeling intact cells followed by cellular lysis and direct 2d-dige analysis. seventy-nine differential spots were analyzed by mass spectrometry ...201727180281
deciphering the regulon of a gntr family regulator via transcriptome and chip-exo analyses and its contribution to virulence in xanthomonas citri.xanthomonas contains a large group of plant-associated species, many of which cause severe diseases on important crops worldwide. six gluconate-operon repressor (gntr) family transcriptional regulators are predicted in xanthomonas, one of which, belonging to the ytra subfamily, plays a prominent role in bacterial virulence. however, the direct targets and comprehensive regulatory profile of ytra remain unknown. here, we performed microarray and high-resolution chromatin immunoprecipitation-exonu ...201726972728
bacterial and plant natriuretic peptides improve plant defense responses against pathogens.plant natriuretic peptides (pnps) are implicated in the regulation of ions and water homeostasis, and their participation in the plant immune response has been also proposed. xanthomonas citri subsp. citri contains a gene encoding a pnp-like protein (xacpnp) that has no homologues in other bacteria. xacpnp mimics its arabidopsis thaliana homolog atpnp-a by modifying host responses to create favorable conditions for pathogen survival. however, the ability of xacpnp to induce plant defense respons ...201728401640
xanthomonas citri minc oscillates from pole to pole to ensure proper cell division and shape.xanthomonas citri (xac) is the causal agent of citrus canker, a disease that affects citrus crops and causes economic impact worldwide. to further characterize cell division in this plant pathogen, we investigated the role of the protein minc in cell division, chromosome segregation, and peptidoglycan incorporation by deleting the gene minc using allele exchange. xac with minc deleted exhibited the classic δmin phenotype observed in other bacteria deleted for min components: minicells and short ...201728769912
structural features of phox, one of the phosphate-binding proteins from pho regulon of xanthomonas citri.in escherichia coli, the atp-binding cassette transporter for phosphate is encoded by the pstscab operon. psts is the periplasmic component responsible for affinity and specificity of the system and has also been related to a regulatory role and chemotaxis during depletion of phosphate. xanthomonas citri has two phosphate-binding proteins: psts and phox, which are differentially expressed under phosphate limitation. in this work, we focused on phox characterization and comparison with psts. the ...201728542513
xanthomonas adaptation to common bean is associated with horizontal transfers of genes encoding tal effectors.common bacterial blight is a devastating bacterial disease of common bean (phaseolus vulgaris) caused by xanthomonas citri pv. fuscans and xanthomonas phaseoli pv. phaseoli. these phylogenetically distant strains are able to cause similar symptoms on common bean, suggesting that they have acquired common genetic determinants of adaptation to common bean. transcription activator-like (tal) effectors are bacterial type iii effectors that are able to induce the expression of host genes to promote i ...201728854875
crystal structure and regulation of the citrus pol iii repressor maf1 by auxin and phosphorylation.maf1 is the main rna polymerase (pol) iii repressor that controls cell growth in eukaryotes. the citrus ortholog, csmaf1, was shown to restrict cell growth in citrus canker disease but its role in plant development and disease is still unclear. we solved the crystal structure of the globular core of csmaf1, which reveals additional structural elements compared with the previously available structure of hmaf1, and explored the dynamics of its flexible regions not present in the structure. csmaf1 ...201728781084
ectopic expression of xylella fastidiosa rpff conferring production of diffusible signal factor in transgenic tobacco and citrus alters pathogen behavior and reduces disease severity.the pathogenicity of xylella fastidiosa is associated with its ability to colonize the xylem of host plants. expression of genes contributing to xylem colonization are suppressed, while those necessary for insect vector acquisition are increased, with increasing concentrations of diffusible signal factor (dsf) whose production is dependent on rpff. we previously demonstrated that transgenic citrus plants ectopically expressing rpff from a citrus strain of x. fastidiosa subsp. pauca exhibited les ...201728777044
the genome of the cotton bacterial blight pathogen xanthomonas citri pv. malvacearum strain msct1.xanthomonas citri pv. malvacearum is a major pathogen of cotton, gossypium hirsutum l.. in this study we report the complete genome of the x. citri pv. malvacearum strain msct1 assembled from long read dna sequencing technology. the msct1 genome is the first x. citri pv. malvacearum genome with complete coding regions for x. citri pv. malvacearum transcriptional activator-like effectors. in addition functional and structural annotations are presented in this study that will provide a foundation ...201728770027
complete genome sequences of three xanthomonas citri strains from texas.the complete genome sequences of three xanthomonas citri strains isolated from lime trees in texas were found to belong to the a(w) group. all carried nearly identical large plasmids with similarity to those of a citrus canker strain from india and to xanthomonads from africa and colombia. all three strains harbored unusual ptha homologs.201728705973
proteomics-based identification of differentially abundant proteins reveals adaptation mechanisms of xanthomonas citri subsp. citri during citrus sinensis infection.xanthomonas citri subsp. citri (xac) is the causal agent of citrus canker. a proteomic analysis under in planta infectious and non-infectious conditions was conducted in order to increase our knowledge about the adaptive process of xac during infection.201728693412
sulfate-binding protein (sbp) from xanthomonas citri: structure and functional insights.the uptake and transport of sulfate in bacteria is mediated by an atp-binding cassette transporter (abc transporter) encoded by sbpcysuwa genes, whose importance has been widely demonstrated due to their relevance in cysteine synthesis and bacterial growth. in xanthomonas citri, the causative agent of canker disease, the expression of components from this abc transporter and others related to uptake of organic sulfur sources has been shown during in vitro growth cultures. in this work, based on ...201728562158
tal effector driven induction of a sweet gene confers susceptibility to bacterial blight of cotton.transcription activator-like (tal) effectors from xanthomonas citri subsp. malvacearum (xcm) are essential for bacterial blight of cotton (bbc). here, by combining transcriptome profiling with tal effector-binding element (ebe) prediction, we show that ghsweet10, encoding a functional sucrose transporter, is induced by avrb6, a tal effector determining xcm pathogenicity. activation of ghsweet10 by designer tal effectors (dtales) restores virulence of xcm avrb6 deletion strains, whereas silencing ...201728537271
'candidatus liberibacter asiaticus' encodes a functional salicylic acid (sa) hydroxylase that degrades sa to suppress plant defenses.pathogens from the fastidious, phloem-restricted 'candidatus liberibacter' species cause the devastating huanglongbing (hlb) disease in citrus worldwide and cause diseases on many solanaceous crops and plants in the apiaceae family. however, little is known about the pathogenic mechanisms due to the difficulty in culturing the corresponding 'ca. liberibacter' species. here, we report that the citrus hlb pathogen 'ca. l. asiaticus' uses an active salicylate hydroxylase saha to degrade salicylic a ...201728488467
the effect of citrus essential oils and their constituents on growth of xanthomonas citri subsp. citri.citrus bacterial canker (cbc) caused by xanthomonas citri subsp. citri (xcc), is the most devastating of the citrus diseases worldwide. during our study, we found that essential oils (eos) of some citrus cultivars are effective on xcc. therefore, it prompted us to determine the plant metabolites responsible for the antibacterial properties. we obtained eos from some locally cultivated citrus by using a clevenger apparatus and their major constituents were identified by gas chromatography/mass sp ...201728420101
bismerthiazol inhibits xanthomonas citri subsp. citri growth and induces differential expression of citrus defense-related genes.citrus canker, caused by xanthomonas citri ssp. citri, is a serious disease that causes substantial economic losses to the citrus industry worldwide. the bactericide bismerthiazol has been used to control rice bacterial blight (x. oryzae pv. oryzae). in this paper, we demonstrate that bismerthiazol can effectively control citrus canker by both inhibiting the growth of x. citri ssp. citri and triggering the plant's host defense response through the expression of several pathogenesis-related genes ...201626882850
temporal transcription profiling of sweet orange in response to ptha4-mediated xanthomonas citri subsp. citri infection.citrus canker, caused by xanthomonas citri subsp. citri, is a devastating disease of most commercial citrus varieties. in our previous study, we analyzed the transcriptional response of 'valencia' sweet orange to x. citri subsp. citri wild-type and ptha4 mutant infection at 48 h postinoculation (hpi). using microarray analysis, two ptha4 targets, cslob1 and cssweet1, were identified. we have shown that ptha4 binds to the effector binding element (ebe) of cslob1 and activates gene expression of t ...201626780431
xacfhab adhesin, an important xanthomonas citri ssp. citri virulence factor, is recognized as a pathogen-associated molecular pattern.adhesion to host tissue is one of the key steps of the bacterial pathogenic process. xanthomonas citri ssp. citri possesses a non-fimbrial adhesin protein, xacfhab, required for bacterial attachment, which we have previously demonstrated to be an important virulence factor for the development of citrus canker. xacfhab is a 4753-residue-long protein with a predicted β-helical fold structure, involved in bacterial aggregation, biofilm formation and adhesion to the host. in this work, to further ch ...201626724481
additive roles of pthas in bacterial growth and pathogenicity associated with nucleotide polymorphisms in effector-binding elements of citrus canker susceptibility genes.citrus canker, caused by xanthomonas citri, affects most commercial citrus varieties. all x. citri strains possess at least one transcription activator-like effector of the ptha family that activates host disease susceptibility (s) genes. the x. citri strain 306 encodes four ptha effectors; nevertheless, only ptha4 is known to elicit cankers on citrus. as none of the pthas act as avirulence factors on citrus, we hypothesized that pthas 1-3 might also contribute to pathogenicity on certain hosts. ...201626709719
reduced susceptibility to xanthomonas citri in transgenic citrus expressing the fls2 receptor from nicotiana benthamiana.overexpression of plant pattern-recognition receptors by genetic engineering provides a novel approach to enhance plant immunity and broad-spectrum disease resistance. citrus canker disease associated with xanthomonas citri is one of the most important diseases damaging citrus production worldwide. in this study, we cloned the fls2 gene from nicotiana benthamiana cdna and inserted it into the binary vector pbinplus/ars to transform hamlin sweet orange and carrizo citrange. transgene presence was ...201626554734
mapping and validation of xanthomonas citri subsp citri genes regulated by putative plant-inducible promoter box (pip-box).citrus canker, caused by the gram-negative bacterium xanthomonas citri subsp citri (xac), is a major disease affecting citriculture worldwide, because of the susceptibility of the host and the lack of efficient control methods. previous studies have reported that some genes of phytopathogenic bacteria possess a consensus nucleotide sequence (ttcgc...n15...ttcgc) designated the "plant-inducible-promoter box" (pip box) located in the promoter region, which is responsible for activating the express ...201627173329
modification of the ptha4 effector binding elements in type i cslob1 promoter using cas9/sgrna to produce transgenic duncan grapefruit alleviating xccδptha4:dcslob1.3 infection.citrus canker caused by xanthomonas citri subspecies citri (xcc) is a severe disease for most commercial citrus cultivars and responsible for significant economic losses worldwide. generating canker-resistant citrus varieties will provide an efficient and sustainable solution to control citrus canker. here, we report our progress in generating canker-resistant grapefruit by modifying the ptha4 effector binding elements (ebes) in the cslob1 promoter (ebeptha4 -cslobp) of the cslob1 (citrus sinens ...201627071672
synthesis and antibacterial evaluation of new sulfone derivatives containing 2-aroxymethyl-1,3,4-oxadiazole/thiadiazole moiety.sulfones are one of the most important classes of agricultural fungicides. to discover new lead compounds with high antibacterial activity, a series of new sulfone derivatives were designed and synthesized by introducing the aroxymethyl moiety into the scaffold of 1,3,4-oxadiazole/thiadiazole sulfones. antibacterial activities against three phytopathogens (xanthomonas oryzae pv. oryzae, ralstonia solanacearum, xanthomonas axonopodis pv. citri.) were assayed in vitro. as compared to the control o ...201628042864
synthesis and antibacterial activity of pyridinium-tailored aromatic amphiphiles.in this letter, the antibacterial activities of pyridinium-tailored aromatic amphiphiles were evaluated by turbidimeter tests in vitro. the bioassays revealed that most of the target compounds exhibit appreciable inhibition activities against the plant pathogenic bacteria xanthomonas oryzae pv. oryzae, ralstonia solanacearum, and xanthomonas axonopodis pv. citri. the half-maximal effective concentrations (ec50) of 2-np-10, 9-ap-10, and 9-ap-7 against these three bacteria were relatively high, wh ...201626832217
synthesis and antibacterial activity of pyridinium-tailored 2,5-substituted-1,3,4-oxadiazole thioether/sulfoxide/sulfone derivatives.by introducing the pyridinium group into 2,5-substituted-1,3,4-oxadiazole, a series of pyridinium-tailored 2,5-substituted-1,3,4-oxadiazole thioether/sulfoxide/sulfone derivatives were obtained, and their antibacterial activities were evaluated via turbidimeter test in vitro. the bioassays reveal that most of the target compounds exhibit better inhibition activities against pathogen xanthomonas oryzae pv. oryzae, ralstonia solanacearum, and xanthomonas axonopodis pv. citri than positive controls ...201626810264
nanofilms of hyaluronan/chitosan assembled layer-by-layer: an antibacterial surface for xylella fastidiosa.in this work, nanofilms of hyaluronan/chitosan (ha/chi) assembled layer by layer were synthesized; their application as a potential antimicrobial material was demonstrated for the phytopathogen xylella fastidiosa, a gram-negative bacterium, here used as a model. for the synthesis, the influence of ph and ionic strength of these natural polymer stem-solutions on final characteristics of the ha/chi nanofilms was studied in detail. the antibacterial effect was evaluated using widefield fluorescence ...201626572322
functional characterization of a lov-histidine kinase photoreceptor from xanthomonas citri subsp. citri.the blue-light (bl) absorbing protein xcc-lov from xanthomonas citri subsp. citri is composed of a lov-domain, a histidine kinase (hk) and a response regulator. spectroscopic characterization of xcc-lov identified intermediates and kinetics of the protein's photocycle. measurements of steady state and time-resolved fluorescence allowed determination of quantum yields for triplet (φt  = 0.68 ± 0.03) and photoproduct formation (φ390  = 0.46 ± 0.05). the lifetime for triplet decay was determined as ...201626172037
genome editing of the disease susceptibility gene cslob1 in citrus confers resistance to citrus canker.citrus is a highly valued tree crop worldwide, while, at the same time, citrus production faces many biotic challenges, including bacterial canker and huanglongbing (hlb). breeding for disease-resistant varieties is the most efficient and sustainable approach to control plant diseases. traditional breeding of citrus varieties is challenging due to multiple limitations, including polyploidy, polyembryony, extended juvenility and long crossing cycles. targeted genome editing technology has the pot ...201627936512
comparative proteomic analysis of xanthomonas citri ssp. citri periplasmic proteins reveals changes in cellular envelope metabolism during in vitro pathogenicity induction.citrus canker is a plant disease caused by gram-negative bacteria from the genus xanthomonas. the most virulent species is xanthomonas citri ssp. citri (xac), which attacks a wide range of citrus hosts. differential proteomic analysis of the periplasm-enriched fraction was performed for xac cells grown in pathogenicity-inducing (xam-m) and pathogenicity-non-inducing (nutrient broth) media using two-dimensional electrophoresis combined with liquid chromatography-tandem mass spectrometry. amongst ...201627798950
structural and functional characterization of the phosphoglucomutase from xanthomonas citri subsp. citri.citrus canker, caused by bacteria xanthomonas citri subsp. citri, can affect all economically important varieties of citrus. studying xanthomonas genes related to the invasive capacity may improve the knowledge on how this works and ultimately use the information to avoid the disease. some annotated genes from xanthomonas citri subsp. citri published genome are addressed to an interesting class of genes named "pathogenicity, virulence and adaptation". one of them is xana, which encodes a predict ...201627567706
differential expression of pectolytic enzyme genes in xanthomonas citri subsp. citri and demonstration that pectate lyase pel3 is required for the formation of citrus canker.bacterial canker, caused by xanthomonas citri subsp. citri (xcc), is one of the most destructive diseases of citrus. the pectolytic enzymes produced by phytobacteria are important virulence factors involved in tissue maceration, electrolyte loss and cell death of host plants. in this study, the promoter activity of the pectolytic enzyme genes pel1, pel2, pel3, pgla, and peh-1 were investigated in xcc xw19 strain using the β-glucuronidase (gus) gene as a reporter. gus activity expressed under the ...201627664718
deletion of pila, a minor pilin-like gene, from xanthomonas citri subsp. citri influences bacterial physiology and pathogenesis.type iv pili (tfp) are widely distributed adhesins of bacterial surfaces. in plant pathogenic bacteria, tfp are involved in host colonization and pathogenesis. xanthomonas citri subsp. citri (xcc) is the phytopathogen responsible for citrus canker disease. in this work, three tfp structural genes, fima, fima1, and pila from xcc were studied. a pila mutant strain from xcc (xccδpila) was constructed and differences in physiological features, such as motilities, adhesion, and biofilm formation, wer ...201627664015
resistance to citrus canker induced by a variant of xanthomonas citri ssp. citri is associated with a hypersensitive cell death response involving autophagy-associated vacuolar processes.xanthomonas citri ssp. citri (x. citri) is the causal agent of asiatic citrus canker, a disease that seriously affects most commercially important citrus species worldwide. we have identified previously a natural variant, x. citri a(t) , that triggers a host-specific defence response in citrus limon. however, the mechanisms involved in this canker disease resistance are unknown. in this work, the defence response induced by x. citri a(t) was assessed by transcriptomic, physiological and ultrastr ...201627647752
virb7 and virb9 interactions are required for the assembly and antibacterial activity of a type iv secretion system.the type iv secretion system (t4ss) from the phytopathogen xanthomonas citri (xac) is a bactericidal nanomachine. the t4ss core complex is a ring composed of multiple copies of virb7-virb9-virb10 subunits. xac-virb7 contains a disordered n-terminal tail (virb7(nt)) that recognizes virb9, and a c-terminal domain (virb7(ct)) involved in virb7 self-association. here, we show that virb7(nt) forms a short β strand upon binding to virb9 and stabilizes it. a tight interaction between them is essential ...201627594685
rapid and accurate identification of xanthomonas citri subspecies citri by fluorescence in situ hybridization.citrus canker is an economically important disease caused by the bacterial pathogen xanthomonas citri subsp. citri (xcc). this organism targets a wide range of citrus plants, including sweet orange, grapefruit, lemon and lime. as xcc is spread by environmental factors such as wind and rain, it is difficult to control its movement once the disease has established. in order to facilitate monitoring of citrus canker we sought to design a novel diagnostic protocol based on fluorescence in situ hybri ...201627492577
an engineered promoter driving expression of a microbial avirulence gene confers recognition of tal effectors and reduces growth of diverse xanthomonas strains in citrus.xanthomonas citri ssp. citri (x. citri), causal agent of citrus canker, uses transcription activator-like effectors (tales) as major pathogenicity factors. tales, which are delivered into plant cells through the type iii secretion system (t3ss), interact with effector binding elements (ebes) in host genomes to activate the expression of downstream susceptibility genes to promote disease. predictably, tales bind ebes in host promoters via known combinations of tale amino acids to dna bases, known ...201627362693
gherf-iib3 regulates the accumulation of jasmonate and leads to enhanced cotton resistance to blight disease.the phytohormone jasmonic acid (ja) and its derivatives, collectively referred to as jasmonates, regulate many developmental processes, but are also involved in the response to numerous abiotic/biotic stresses. thus far, powerful reverse genetic strategies employing perception, signalling or biosynthesis mutants have broadly contributed to our understanding of the role of ja in the plant stress response and development, as has the chemical gain-of-function approach based on exogenous application ...201627291786
deuterium-labeled precursor feeding reveals a new paba-containing meroterpenoid from the mango pathogen xanthomonas citri pv. mangiferaeindicae.a new para-aminobenzoic-acid-containing natural product from the mango pathogenic organism xanthomonas citri pv. mangiferaeindicae is described. by means of stable isotope precursor feeding combined with nontargeted lc-ms/ms, the generated spectra were clustered and visualized in a molecular network. this led to the identification of a new member of the meroterpenoids, termed xanthomonic acid, which is composed of an isoprenylated para-aminobenzoic acid. in vitro cytotoxicity assays demonstrated ...201627232656
xanthomonas citri ssp. citri requires the outer membrane porin oprb for maximal virulence and biofilm formation.xanthomonas citri ssp. citri (xcc) causes canker disease in citrus, and biofilm formation is critical for the disease cycle. oprb (outer membrane protein b) has been shown previously to be more abundant in xcc biofilms compared with the planktonic state. in this work, we showed that the loss of oprb in an oprb mutant abolishes bacterial biofilm formation and adherence to the host, and also compromises virulence and efficient epiphytic survival of the bacteria. moreover, the oprb mutant is impair ...201627226289
antibacterial activity of cyclo(l-pro-l-tyr) and cyclo(d-pro-l-tyr) from streptomyces sp. strain 22-4 against phytopathogenic bacteria.two bioactive cyclic dipeptides, cyclo(l-pro-l-tyr) and cyclo(d-pro-l-tyr), were isolated from the culture broth of streptomyces sp. strain 22-4 and tested against three economically important plant pathogens, xanthomonas axonopodis pv. citri, ralstonia solanacearum and clavibacter michiganensis. both cyclic dipeptides were active against x. axonopodis pv. citri and r. solanacearum with mic of 31.25 μg/ml. no activity could be observed against c. michiganensis.201626469746
mechanistic and evolutionary insights from comparative enzymology of phosphomonoesterases and phosphodiesterases across the alkaline phosphatase superfamily.naively one might have expected an early division between phosphate monoesterases and diesterases of the alkaline phosphatase (ap) superfamily. on the contrary, prior results and our structural and biochemical analyses of phosphate monoesterase pafa, from chryseobacterium meningosepticum, indicate similarities to a superfamily phosphate diesterase [xanthomonas citri nucleotide pyrophosphatase/phosphodiesterase (npp)] and distinct differences from the three metal ion ap superfamily monoesterase, ...201627670607
the mosaic type iv secretion systems.escherichia coli and other gram-negative and -positive bacteria employ type iv secretion systems (t4sss) to translocate dna and protein substrates, generally by contact-dependent mechanisms, to other cells. the t4sss functionally encompass two major subfamilies, the conjugation systems and the effector translocators. the conjugation systems are responsible for interbacterial transfer of antibiotic resistance genes, virulence determinants, and genes encoding other traits of potential benefit to t ...201627735785
trea codifies for a trehalase with involvement in xanthomonas citri subsp. citri pathogenicity.citrus canker, caused by the bacterium xanthomonas citri subsp. citri (xcc), is a severe disease of citrus. xcc presents broad spectrum of citrus hosts including economically important species whereas x. fuscans subsp. aurantifolii-type c (xauc) causes a milder disease and only infects citrus aurantifolia. trehalase catalyzes hydrolysis of the disaccharide trehalose, a sugar that has been reported to be related to xcc pathogenicity. we expressed the recombinant gene product and assessed xcc treh ...201627611974
a tale of two sugars: trehalose 6-phosphate and sucrose.trehalose 6-phosphate (tre6p), the intermediate of trehalose biosynthesis, is an essential signal metabolite in plants, linking growth and development to carbon status. the suc-tre6p nexus model postulates that tre6p is both a signal and negative feedback regulator of suc levels, forming part of a mechanism to maintain suc levels within an optimal range and functionally comparable to the insulin-glucagon system for regulating blood glc levels in animals. the target range and sensitivity of the t ...201627482078
overexpression of a modified plant thionin enhances disease resistance to citrus canker and huanglongbing (hlb).huanglongbing (hlb or citrus greening disease) caused by candidatus liberibacter asiaticus (las) is a great threat to the us citrus industry. there are no proven strategies to eliminate hlb disease and no cultivar has been identified with strong hlb resistance. citrus canker is also an economically important disease associated with a bacterial pathogen (xanthomonas citri). in this study, we characterized endogenous citrus thionins and investigated their expression in different citrus tissues. si ...201627499757
comparison of droplet digital pcr and quantitative pcr assays for quantitative detection of xanthomonas citri subsp. citri.droplet digital polymerase chain reaction (ddpcr) is a novel molecular biology technique providing absolute quantification of target nucleic acids without the need for an external calibrator. despite its emerging applications in medical diagnosis, there are few reports of its use for the detection of plant pathogens. this work was designed to assess the diagnosis potential of the ddpcr for absolute quantitative detection of xanthomonas citri subsp. citri, a quarantine plant pathogenic bacterium ...201627427975
use of an improved matching algorithm to select scaffolds for enzyme design based on a complex active site model.active site preorganization helps native enzymes electrostatically stabilize the transition state better than the ground state for their primary substrates and achieve significant rate enhancement. in this report, we hypothesize that a complex active site model for active site preorganization modeling should help to create preorganized active site design and afford higher starting activities towards target reactions. our matching algorithm prodamatch was improved by invoking effective pruning st ...201627243223
genetic and molecular basis of kingella kingae encapsulation.kingella kingae is a common cause of invasive disease in young children and was recently found to produce a polysaccharide capsule containing n-acetylgalactosamine (galnac) and β-3-deoxy-d-manno-octulosonic acid (βkdo). given the role of capsules as important virulence factors and effective vaccine antigens, we set out to determine the genetic determinants of k. kingae encapsulation. using a transposon library and a screen for nonencapsulated mutants, we identified the previously identified ctra ...201627045037
correction: identification of an extracellular endoglucanase that is required for full virulence in xanthomonas citri subsp. citri.[this corrects the article doi: 10.1371/journal.pone.0151017.].201627214201
a survey of fls2 genes from multiple citrus species identifies candidates for enhancing disease resistance to xanthomonas citri ssp. citri.pathogen-associated molecular patterns (pamps)-triggered immunity (pti) is an important component of plant innate immunity. in a previous study, we showed that the pamp flg22 from xanthomonas citri ssp. citri (xflg22), the causal agent of citrus canker, induced pti in citrus, which correlated with the observed levels of canker resistance. here, we identified and sequenced two bacterial flagellin/flg22 receptors (fls2-1 and fls2-2) from 'duncan' grapefruit (citrus paradisi, cpfls2-1 and cpfls2-2) ...201627222722
development of a microemulsion formulation for antimicrobial seca inhibitors.in our previous study, we have identified five antimicrobial small molecules via structure based design, which inhibit seca of candidatus liberibacter asiaticus (las). seca is a critical protein translocase atpase subunit and is involved in pre-protein translocation across and integration into the cellular membrane in bacteria. in this study, eleven compounds were identified using similarity search method based on the five lead seca inhibitors identified previously. the identified seca inhibitor ...201626963811
a protein expression system for tandem affinity purification in xanthomonas citri subsp. citri.citrus canker, caused by the gram-negative bacterium xanthomonas citri subsp. citri (xac), is one of the most devastating diseases to affect citrus crops. there is no treatment for citrus canker; effective control against the spread of xac is usually achieved by the elimination of affected plants along with that of asymptomatic neighbors. an in depth understanding of the pathogen is the keystone for understanding of the disease; to this effect we are committed to the development of strategies to ...201626991273
bioactive organocopper compound from pseudomonas aeruginosa inhibits the growth of xanthomonas citri subsp. citri.citrus canker is a very destructive disease of citrus species. the challenge is to find new compounds that show strong antibiotic activity and low toxicity to plants and the environment. the objectives of the present study were (1) to extract, purify and evaluate the secondary metabolites with antibiotic activity produced by pseudomonas aeruginosa lv strain in vitro against xanthomonas citri subsp. citri (strain 306), (2) to determine the potential of semi-purified secondary metabolites in folia ...201626903992
possible role of plant volatiles in tolerance against huanglongbing in citrus.volatile organic compounds (voc) play an important role in protecting plants from insect and pathogen attack. in this study, we investigated the leaf volatile profiles of 14 citrus varieties. the voc in citrus leaves were extracted with n-hexane and analyzed using gas chromatography-mass spectrometry (gc-ms). overall, 4six volatile compounds were identified in the n-hexane extract from citrus leaves. most of the detected compounds belonged to 3 main groups (monoterpenes, sesquiterpenes, and alip ...201626829496
citrus breeding, genetics and genomics in japan.citrus is one of the most cultivated fruits in the world, and satsuma mandarin (citrus unshiu marc.) is a major cultivated citrus in japan. many excellent cultivars derived from satsuma mandarin have been released through the improvement of mandarins using a conventional breeding method. the citrus breeding program is a lengthy process owing to the long juvenility, and it is predicted that marker-assisted selection (mas) will overcome the obstacle and improve the efficiency of conventional breed ...201627069387
disruption of the cara gene in pseudomonas syringae results in reduced fitness and alters motility.pseudomonas syringae infects diverse plant species and is widely used in the study of effector function and the molecular basis of disease. although the relationship between bacterial metabolism, nutrient acquisition and virulence has attracted increasing attention in bacterial pathology, there is limited knowledge regarding these studies in pseudomonas syringae. the aim of this study was to investigate the function of the cara gene and the small rna p32, and characterize the regulation of these ...201627558694
priming by hexanoic acid induce activation of mevalonic and linolenic pathways and promotes the emission of plant volatiles.hexanoic acid (hx) is a short natural monocarboxylic acid present in some fruits and plants. previous studies reported that soil drench application of this acid induces effective resistance in tomato plants against botrytis cinerea and pseudomonas syringae and in citrus against alternaria alternata and xanthomonas citri. in this work, we performed an in deep study of the metabolic changes produced in citrus by the application of hx in response to the challenge pathogen a. alternata, focusing on ...201627148319
katg, the bifunctional catalase of xanthomonas citri subsp. citri, responds to hydrogen peroxide and contributes to epiphytic survival on citrus leaves.xanthomonas citri subsp. citri (xcc) is the bacterium responsible for citrus canker. this bacterium is exposed to reactive oxygen species (ros) at different points during its life cycle, including those normally produced by aerobic respiration or upon exposition to ultraviolet (uv) radiation. moreover, ros are key components of the host immune response. among enzymatic ros-detoxifying mechanisms, catalases eliminate h2o2, avoiding the potential damage caused by this specie. xcc genome includes f ...201626990197
identification of an extracellular endoglucanase that is required for full virulence in xanthomonas citri subsp. citri.xanthomonas citri subsp. citri causes citrus canker disease, which is characterized by the formation of water-soaked lesions, white or yellow spongy pustules and brown corky canker. in this work, we report the contribution of extracellular endoglucanase to canker development during infection. the ectopic expression of nine putative cellulases in escherichia coli indicated that two endoglucanases, bglc3 and engxca, show carboxymethyl cellulase activity. both bglc3 and engxca genes were transcribe ...201626950296
interaction network and mass spectrometry data of xanthomonas citri subsp. citri surface proteins from differential proteomic analysis of infectious and non-infectious cells.here we provide the mass-spectrometry and in silico interaction network dataset of proteins identified on our research article on surface proteomic analysis from xanthomonas citri subsp. citri (xac) cells grown in vivo (infectious) and in vitro (non-infectious, control) by 2d-dige approach. fluorescence labeling of proteins were performed on intact cells followed by cellular lysis and labeled spots from 2d gel differing in abundance between the two conditions (anova, p-value<0.05) were analyzed ...201627595129
presence of extracellular dna during biofilm formation by xanthomonas citri subsp. citri strains with different host range.xanthomonas citri subsp. citri (xcc) a strain causes citrus bacterial canker, a serious leaf, fruit and stem spotting disease of several citrus species. x. alfalfae subsp. citrumelonis (xac) is the cause of citrus bacterial spot, a minor disease of citrus nursery plants and x. campestris pv. campestris (xc) is a systemic pathogen that causes black rot of cabbage. xanthomonas spp. form biofilms in planta that facilitate the host infection process. herein, the role of extracellular dna (edna) was ...201627248687
type ii toxin-antitoxin distribution and adaptive aspects on xanthomonas genomes: focus on xanthomonas citri.prokaryotic toxin-antitoxin (ta) systems were first described as being designed to prevent plasmid loss in bacteria. however, with the increase in prokaryotic genome sequencing, recently many tas have been found in bacterial chromosomes, having other biological functions, such as environmental stress response. to date, only few studies have focused on ta systems in phytopathogens, and their possible impact on the bacterial fitness. this may be especially important for pathogens like xanthomonas ...201627242687
the atp-dependent rna helicase hrpb plays an important role in motility and biofilm formation in xanthomonas citri subsp. citri.rna helicases are enzymes that catalyze the separation of double-stranded rna (dsrna) using the free energy of atp binding and hydrolysis. dead/deah families participate in many different aspects of rna metabolism, including rna synthesis, rna folding, rna-rna interactions, rna localization and rna degradation. several important bacterial dead/deah-box rna helicases have been extensively studied. in this study, we characterize the atp-dependent rna helicase encoded by the hrpb (xac0293) gene usi ...201627005008
mechanistic insights into c-di-gmp-dependent control of the biofilm regulator fleq from pseudomonas aeruginosa.bacterial biofilm formation during chronic infections confers increased fitness, antibiotic tolerance, and cytotoxicity. in many pathogens, the transition from a planktonic lifestyle to collaborative, sessile biofilms represents a regulated process orchestrated by the intracellular second-messenger c-di-gmp. a main effector for c-di-gmp signaling in the opportunistic pathogen pseudomonas aeruginosa is the transcription regulator fleq. fleq is a bacterial enhancer-binding protein (bebp) with a ce ...201626712005
mechanistic insights into c-di-gmp-dependent control of the biofilm regulator fleq from pseudomonas aeruginosa.bacterial biofilm formation during chronic infections confers increased fitness, antibiotic tolerance, and cytotoxicity. in many pathogens, the transition from a planktonic lifestyle to collaborative, sessile biofilms represents a regulated process orchestrated by the intracellular second-messenger c-di-gmp. a main effector for c-di-gmp signaling in the opportunistic pathogen pseudomonas aeruginosa is the transcription regulator fleq. fleq is a bacterial enhancer-binding protein (bebp) with a ce ...201626712005
comparative genomics of pseudomonas syringae pathovar tomato reveals novel chemotaxis pathways associated with motility and plant pathogenicity.the majority of bacterial foliar plant pathogens must invade the apoplast of host plants through points of ingress, such as stomata or wounds, to replicate to high population density and cause disease. how pathogens navigate plant surfaces to locate invasion sites remains poorly understood. many bacteria use chemical-directed regulation of flagellar rotation, a process known as chemotaxis, to move towards favorable environmental conditions. chemotactic sensing of the plant surface is a potential ...201627812402
multiple locus variable number of tandem repeat analysis: a molecular genotyping tool for paenibacillus larvae.american foulbrood, caused by paenibacillus larvae, is the most severe bacterial disease of honey bees (apis mellifera). to perform genotyping of p. larvae in an epidemiological context, there is a need of a fast and cheap method with a high resolution. here, we propose multiple locus variable number of tandem repeat analysis (mlva). mlva has been used for typing a collection of 209 p. larvae strains from which 23 different mlva types could be identified. moreover, the developed methodology not ...201627365124
mechanism and function of type iv secretion during infection of the human host.bacterial pathogens employ type iv secretion systems (t4sss) for various purposes to aid in survival and proliferation in eukaryotic hosts. one large t4ss subfamily, the conjugation systems, confers a selective advantage to the invading pathogen in clinical settings through dissemination of antibiotic resistance genes and virulence traits. besides their intrinsic importance as principle contributors to the emergence of multiply drug-resistant "superbugs," detailed studies of these highly tractab ...201627337453
the role of bacterial secretion systems in the virulence of gram-negative airway pathogens associated with cystic fibrosis.cystic fibrosis (cf) is the most common lethal inherited disorder in caucasians. it is caused by mutation of the cf transmembrane conductance regulator (cftr) gene. a defect in the cftr ion channel causes a dramatic change in the composition of the airway surface fluid, leading to a highly viscous mucus layer. in healthy individuals, the majority of bacteria trapped in the mucus layer are removed and destroyed by mucociliary clearance. however, in the lungs of patients with cf, the mucociliary c ...201627625638
biofilms and cyclic di-gmp (c-di-gmp) signaling: lessons from pseudomonas aeruginosa and other bacteria.the cyclic di-gmp (c-di-gmp) second messenger represents a signaling system that regulates many bacterial behaviors and is of key importance for driving the lifestyle switch between motile loner cells and biofilm formers. this review provides an up-to-date compendium of c-di-gmp pathways connected to biofilm formation, biofilm-associated motilities, and other functionalities in the ubiquitous and opportunistic human pathogen pseudomonas aeruginosa this bacterium is frequently adopted as a model ...201627129226
unravelling potential virulence factor candidates in xanthomonas citri. subsp. citri by secretome analysis.citrus canker is a major disease affecting citrus production in brazil. it's mainly caused by xanthomonas citri subsp. citri strain 306 pathotype a (xac). we analysed the differential expression of proteins secreted by wild type xac and an asymptomatic mutant for hrpb4 (δhrpb4) grown in nutrient broth (nb) and a medium mimicking growth conditions in the plant (xam1). this allowed the identification of 55 secreted proteins, of which 37 were secreted by both strains when cultured in xam1. in this ...201626925342
virus-induced gene silencing-based functional analyses revealed the involvement of several putative trehalose-6-phosphate synthase/phosphatase genes in disease resistance against botrytis cinerea and pseudomonas syringae pv. tomato dc3000 in tomato.trehalose and its metabolism have been demonstrated to play important roles in control of plant growth, development, and stress responses. however, direct genetic evidence supporting the functions of trehalose and its metabolism in defense response against pathogens is lacking. in the present study, genome-wide characterization of putative trehalose-related genes identified 11 sltpss for trehalose-6-phosphate synthase, 8 sltpps for trehalose-6-phosphate phosphatase and one sltre1 for trehalase i ...201627540389
expression of a recombinant anti-hiv and anti-tumor protein, map30, in nicotiana tobacum hairy roots: a ph-stable and thermophilic antimicrobial protein.in contrast to conventional antibiotics, which microorganisms can readily evade, it is nearly impossible for a microbial strain that is sensitive to antimicrobial proteins to convert to a resistant strain. therefore, antimicrobial proteins and peptides that are promising alternative candidates for the control of bacterial infections are under investigation. the map30 protein of momordica charantia is a valuable type i ribosome-inactivating protein (rip) with anti-hiv and anti-tumor activities. w ...201627459300
a novel multilocus variable number tandem repeat analysis typing scheme for african phylotype iii strains of the ralstonia solanacearum species complex.background. reliable genotyping that provides an accurate description of diversity in the context of pathogen emergence is required for the establishment of strategies to improve disease management. multilocus variable number tandem repeat analysis (mlva) is a valuable genotyping method. it can be performed at small evolutionary scales where high discriminatory power is needed. strains of the ralstonia solanacearum species complex (rssc) are highly genetically diverse. these destructive pathogen ...201627168969
iron is a signal for stenotrophomonas maltophilia biofilm formation, oxidative stress response, omps expression, and virulence.stenotrophomonas maltophilia is an emerging nosocomial pathogen. in many bacteria iron availability regulates, through the fur system, not only iron homeostasis but also virulence. the aim of this work was to assess the role of iron on s. maltophilia biofilm formation, eps production, oxidative stress response, omps regulation, quorum sensing (qs), and virulence. studies were done on k279a and its isogenic fur mutant f60 cultured in the presence or absence of dipyridyl. this is the first report ...201526388863
the dsf family of cell-cell signals: an expanding class of bacterial virulence regulators.many pathogenic bacteria use cell-cell signaling systems involving the synthesis and perception of diffusible signal molecules to control virulence as a response to cell density or confinement to niches. bacteria produce signals of diverse structural classes. signal molecules of the diffusible signal factor (dsf) family are cis-2-unsaturated fatty acids. the paradigm is cis-11-methyl-2-dodecenoic acid from xanthomonas campestris pv. campestris (xcc), which controls virulence in this plant pathog ...201526181439
surface polysaccharide mutants reveal that absence of o antigen reduces biofilm formation of actinobacillus pleuropneumoniae.actinobacillus pleuropneumoniae is a gram-negative bacterium belonging to the pasteurellaceae family and the causative agent of porcine pleuropneumonia, a highly contagious lung disease causing important economic losses. surface polysaccharides, including lipopolysaccharides (lps) and capsular polysaccharides (cps), are implicated in the adhesion and virulence of a. pleuropneumoniae, but their role in biofilm formation is still unclear. in this study, we investigated the requirement for these su ...201526483403
surface polysaccharide mutants reveal that absence of o antigen reduces biofilm formation of actinobacillus pleuropneumoniae.actinobacillus pleuropneumoniae is a gram-negative bacterium belonging to the pasteurellaceae family and the causative agent of porcine pleuropneumonia, a highly contagious lung disease causing important economic losses. surface polysaccharides, including lipopolysaccharides (lps) and capsular polysaccharides (cps), are implicated in the adhesion and virulence of a. pleuropneumoniae, but their role in biofilm formation is still unclear. in this study, we investigated the requirement for these su ...201526483403
antibacterial activity of stenotrophomonas maltophilia endolysin p28 against both gram-positive and gram-negative bacteria.maltocin p28 is a phage-tail like bacteriocin produced by stenotrophomonas maltophilia p28. the orf8 of maltocin p28 gene cluster is predicted to encode an endolysin and we name it endolysin p28. sequence analysis revealed that it contains the lysozyme_like superfamily conserved domain. endolysin p28 has the four consensus motifs as that of escherichia coli phage lambda gpr. in this study, endolysin p28 was expressed in e. coli bl21 (de3) and purified with a c-terminal oligo-histidine tag. the a ...201526635765
complete sequence and detailed analysis of the first indigenous plasmid from xanthomonas oryzae pv. oryzicola.bacterial plasmids have a major impact on metabolic function and adaptation of their hosts. an indigenous plasmid was identified in a chinese isolate (gx01) of the invasive phytopathogen xanthomonas oryzae pv. oryzicola (xoc), the causal agent of rice bacterial leaf streak (bls). to elucidate the biological functions of the plasmid, we have sequenced and comprehensively annotated the plasmid.201526498126
lipopolysaccharide o-chain core region required for cellular cohesion and compaction of in vitro and root biofilms developed by rhizobium leguminosarum.the formation of biofilms is an important survival strategy allowing rhizobia to live on soil particles and plant roots. within the microcolonies of the biofilm developed by rhizobium leguminosarum, rhizobial cells interact tightly through lateral and polar connections, forming organized and compact cell aggregates. these microcolonies are embedded in a biofilm matrix, whose main component is the acidic exopolysaccharide (eps). our work shows that the o-chain core region of the r. leguminosarum ...201525416773
structure and function of a short lov protein from the marine phototrophic bacterium dinoroseobacter shibae.light, oxygen, voltage (lov) domains are widely distributed in plants, algae, fungi, bacteria, and represent the photo-responsive domains of various blue-light photoreceptor proteins. their photocycle involves the blue-light triggered adduct formation between the c(4a) atom of a non-covalently bound flavin chromophore and the sulfur atom of a conserved cysteine in the lov sensor domain. lov proteins show considerable variation in the structure of n- and c-terminal elements which flank the lov co ...201525887755
the dual nature of trehalose in citrus canker disease: a virulence factor for xanthomonas citri subsp. citri and a trigger for plant defence responses.xanthomonas citri subsp. citri (xcc) is a bacterial pathogen that causes citrus canker in susceptible citrus spp. the xcc genome contains genes encoding enzymes from three separate pathways of trehalose biosynthesis. expression of genes encoding trehalose-6-phosphate synthase (otsa) and trehalose phosphatase (otsb) was highly induced during canker development, suggesting that the two-step pathway of trehalose biosynthesis via trehalose-6-phosphate has a function in pathogenesis. this pathway was ...201525770587
effect of x-irradiation on citrus canker pathogen xanthomonas citri subsp. citri of satsuma mandarin fruits.citrus canker caused by xanthomonas citri subsp. citri (xcc) is one of the most important bacterial diseases of citrus. because citrus canker is not found in many countries including european union and australia, xcc is strictly regulated in order to prevent its spread. in this study, the effects of x-irradiation on xcc growth either in the suspension or on the surface of citrus fruits were investigated. the suspension containing 1×10(7) cfu/ml of xcc was irradiated with different absorbed doses ...201526672670
type iii secretion system translocon component eseb forms filaments on and mediates autoaggregation of and biofilm formation by edwardsiella tarda.the type iii secretion system (t3ss) of edwardsiella tarda plays an important role in infection by translocating effector proteins into host cells. eseb, a component required for effector translocation, is reported to mediate autoaggregation of e. tarda. in this study, we demonstrate that eseb forms filamentous appendages on the surface of e. tarda and is required for biofilm formation by e. tarda in dulbecco's modified eagle's medium (dmem). biofilm formation by e. tarda in dmem does not requir ...201526116669
pqqe from methylobacterium extorquens am1: a radical s-adenosyl-l-methionine enzyme with an unusual tolerance to oxygen.methylobacterium extorquens am1 is an aerobic facultative methylotroph known to secrete pyrroloquinoline quinone (pqq), a cofactor of a number of bacterial dehydrogenases, into the culture medium. to elucidate the molecular mechanism of pqq biosynthesis, we are focusing on pqqe which is believed to be the enzyme catalysing the first reaction of the pathway. pqqe belongs to the radical s-adenosyl-l-methionine (sam) superfamily, in which most, if not all, enzymes are very sensitive to dissolved ox ...201526188050
pqqe from methylobacterium extorquens am1: a radical s-adenosyl-l-methionine enzyme with an unusual tolerance to oxygen.methylobacterium extorquens am1 is an aerobic facultative methylotroph known to secrete pyrroloquinoline quinone (pqq), a cofactor of a number of bacterial dehydrogenases, into the culture medium. to elucidate the molecular mechanism of pqq biosynthesis, we are focusing on pqqe which is believed to be the enzyme catalysing the first reaction of the pathway. pqqe belongs to the radical s-adenosyl-l-methionine (sam) superfamily, in which most, if not all, enzymes are very sensitive to dissolved ox ...201526188050
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