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cell wall integrity signaling and innate immunity in plants.all plant pathogens and parasites have had to develop strategies to overcome cell walls in order to access the host's cytoplasm. as a mechanically strong, multi-layered composite exoskeleton, the cell wall not only enables plants to grow tall but also protects them from such attacks. many plant pathogens employ an arsenal of cell wall degrading enzymes, and it has long been thought that the detection of breaches in wall integrity contributes to the induction of defense. cell wall fragments are d ...201223248636
the magnaporthe oryzae effector avrpiz-t targets the ring e3 ubiquitin ligase apip6 to suppress pathogen-associated molecular pattern-triggered immunity in rice.although the functions of a few effector proteins produced by bacterial and oomycete plant pathogens have been elucidated in recent years, information for the vast majority of pathogen effectors is still lacking, particularly for those of plant-pathogenic fungi. here, we show that the avirulence effector avrpiz-t from the rice blast fungus magnaporthe oryzae preferentially accumulates in the specialized structure called the biotrophic interfacial complex and is then translocated into rice (oryza ...201223204406
contribution of lateral gene transfers to the genome composition and parasitic ability of root-knot nematodes.lateral gene transfers (lgt), species to species transmission of genes by means other than direct inheritance from a common ancestor, have played significant role in shaping prokaryotic genomes and are involved in gain or transfer of important biological processes. whether lgt significantly contributed to the composition of an animal genome is currently unclear. in nematodes, multiple lgt are suspected to have favored emergence of plant-parasitism. with the availability of whole genome sequences ...201223226415
the pepper extracellular xyloglucan-specific endo-β-1,4-glucanase inhibitor protein gene, caxegip1, is required for plant cell death and defense responses.plants produce various proteinaceous inhibitors to protect themselves against microbial pathogen attack. a xyloglucan-specific endo-β-1,4-glucanase inhibitor1 gene, caxegip1, was isolated and functionally characterized in pepper (capsicum annuum) plants. caxegip1 was rapidly and strongly induced in pepper leaves infected with avirulent xanthomonas campestris pv vesicatoria, and purified caxegip1 protein significantly inhibited the hydrolytic activity of the glycoside hydrolase74 family xylogluca ...201223093361
the pepper extracellular xyloglucan-specific endo-β-1,4-glucanase inhibitor protein gene, caxegip1, is required for plant cell death and defense responses.plants produce various proteinaceous inhibitors to protect themselves against microbial pathogen attack. a xyloglucan-specific endo-β-1,4-glucanase inhibitor1 gene, caxegip1, was isolated and functionally characterized in pepper (capsicum annuum) plants. caxegip1 was rapidly and strongly induced in pepper leaves infected with avirulent xanthomonas campestris pv vesicatoria, and purified caxegip1 protein significantly inhibited the hydrolytic activity of the glycoside hydrolase74 family xylogluca ...201223093361
interpreting genomic data via entropic dissection.since the emergence of high-throughput genome sequencing platforms and more recently the next-generation platforms, the genome databases are growing at an astronomical rate. tremendous efforts have been invested in recent years in understanding intriguing complexities beneath the vast ocean of genomic data. this is apparent in the spurt of computational methods for interpreting these data in the past few years. genomic data interpretation is notoriously difficult, partly owing to the inherent he ...201223036836
interpreting genomic data via entropic dissection.since the emergence of high-throughput genome sequencing platforms and more recently the next-generation platforms, the genome databases are growing at an astronomical rate. tremendous efforts have been invested in recent years in understanding intriguing complexities beneath the vast ocean of genomic data. this is apparent in the spurt of computational methods for interpreting these data in the past few years. genomic data interpretation is notoriously difficult, partly owing to the inherent he ...201223036836
synergistic activation of the pathogenicity-related proline iminopeptidase gene in xanthomonas campestris pv. campestris by hrpx and a luxr homolog.xanthomonas campestris pv. campestris strain 8004 contains an orphan quorum-sensing (qs) locus, xccr-pip(xcc), in which the proline iminopeptidase (pip(xcc)) gene (where "xcc" indicates that the pip gene is from x. campestris pv. campestris) is positively regulated by the luxr homologue xccr by binding to the luxxc box of the pip(xcc) promoter. the disruption of pip(xcc) significantly attenuated the virulence of x. campestris pv. campestris. an imperfect plant-inducible promoter (pip) box is loc ...201222865058
"listening in" on how a bacterium takes over the plant vascular system.bacteria that infect the plant vascular system are among the most destructive kind of plant pathogens because pathogen proliferation in the vascular system will sooner or later shut down the plant's water and nutrient supply and necessarily lead to wilting and, in the worst case, death of the entire plant. how bacterial plant pathogens adapted to life in the plant vascular system is still poorly understood. as described in a recent article, caitilyn allen and her group studied the archetypical v ...201222967979
phylogenetic analysis of a gene cluster encoding an additional, rhizobial-like type iii secretion system that is narrowly distributed among pseudomonas syringae strains.the central role of type iii secretion systems (t3ss) in bacteria-plant interactions is well established, yet unexpected findings are being uncovered through bacterial genome sequencing. some pseudomonas syringae strains possess an uncharacterized cluster of genes encoding putative components of a second t3ss (t3ss-2) in addition to the well characterized hrc1 t3ss which is associated with disease lesions in host plants and with the triggering of hypersensitive response in non-host plants. the a ...201222937899
the bacterium pantoea stewartii uses two different type iii secretion systems to colonize its plant host and insect vector.plant- and animal-pathogenic bacteria utilize phylogenetically distinct type iii secretion systems (t3ss) that produce needle-like injectisomes or pili for the delivery of effector proteins into host cells. pantoea stewartii subsp. stewartii (herein referred to as p. stewartii), the causative agent of stewart's bacterial wilt and leaf blight of maize, carries phylogenetically distinct t3sss. in addition to an hrc-hrp t3ss, known to be essential for maize pathogenesis, p. stewartii has a second t ...201222773631
srfj, a salmonella type iii secretion system effector regulated by phop, rcsb, and iolr.virulence-related type iii secretion systems are present in many gram-negative bacterial pathogens. these complex devices translocate proteins, called effectors, from the bacterium into the eukaryotic host cell. here, we identify the product of srfj, a salmonella enterica serovar typhimurium gene regulated by ssrb, as a new substrate of the type iii secretion system encoded by salmonella pathogenicity island 2. the n-terminal 20-amino-acid segment of srfj was recognized as a functional secretion ...201222661691
evolution of two-component signal transduction systems.to exist in a wide range of environmental niches, bacteria must sense and respond to a variety of external signals. a primary means by which this occurs is through two-component signal transduction pathways, typically composed of a sensor histidine kinase that receives the input stimuli and then phosphorylates a response regulator that effects an appropriate change in cellular physiology. histidine kinases and response regulators have an intrinsic modularity that separates signal input, phosphot ...201222746333
aspartate oxidase plays an important role in arabidopsis stomatal immunity.perception of pathogen-associated molecular patterns (pamps), such as bacterial flagellin (or the peptide flg22), by surface-localized receptors activates defense responses and subsequent immunity. in a previous forward-genetic screen aimed at the identification of arabidopsis (arabidopsis thaliana) flagellin-insensitive (fin) mutants, we isolated fin4, which is severely affected in flg22-triggered reactive oxygen species (ros) bursts. here, we report that fin4 encodes the chloroplastic enzyme a ...201222730426
mitogen-activated protein (map) kinases in plant metal stress: regulation and responses in comparison to other biotic and abiotic stresses.exposure of plants to toxic concentrations of metals leads to disruption of the cellular redox status followed by an accumulation of reactive oxygen species (ros). ros, like hydrogen peroxide, can act as signaling molecules in the cell and induce signaling via mitogen-activated protein kinase (mapk) cascades. mapk cascades are evolutionary conserved signal transduction modules, able to convert extracellular signals to appropriate cellular responses. in this review, our current understanding abou ...201222837729
high-throughput genomic sequencing of cassava bacterial blight strains identifies conserved effectors to target for durable resistance.cassava bacterial blight (cbb), incited by xanthomonas axonopodis pv. manihotis (xam), is the most important bacterial disease of cassava, a staple food source for millions of people in developing countries. here we present a widely applicable strategy for elucidating the virulence components of a pathogen population. we report illumina-based draft genomes for 65 xam strains and deduce the phylogenetic relatedness of xam across the areas where cassava is grown. using an extensive database of eff ...201222699502
ubiquitination during plant immune signaling. 201222689893
the type iii secretion system is necessary for the development of a pathogenic and endophytic interaction between herbaspirillum rubrisubalbicans and poaceae.herbaspirillum rubrisubalbicans was first identified as a bacterial plant pathogen, causing the mottled stripe disease in sugarcane. h. rubrisubalbicans can also associate with various plants of economic interest in a non pathogenic manner.201222672506
hydrogen peroxide-a central hub for information flow in plant cells.hydrogen peroxide (h(2)o(2)) was initially recognized as a toxic reactive oxygen species, able to cause damage to a variety of cellular structures. however, it became clear in the last decade that h(2)o(2) can also act as a potent signalling molecule, involved in a plethora of physiological functions.201222708052
functional analysis of nopm, a novel e3 ubiquitin ligase (nel) domain effector of rhizobium sp. strain ngr234.type 3 effector proteins secreted via the bacterial type 3 secretion system (t3ss) are not only virulence factors of pathogenic bacteria, but also influence symbiotic interactions between nitrogen-fixing nodule bacteria (rhizobia) and leguminous host plants. in this study, we characterized nopm (nodulation outer protein m) of rhizobium sp. strain ngr234, which shows sequence similarities with novel e3 ubiquitin ligase (nel) domain effectors from the human pathogens shigella flexneri and salomone ...201222615567
metabolic adaptation of ralstonia solanacearum during plant infection: a methionine biosynthesis case study.mete and meth are two distinct enzymes that catalyze a similar biochemical reaction during the last step of methionine biosynthesis, meth being a cobalamin-dependent enzyme whereas mete activity is cobalamin-independent. in this work, we show that the last step of methionine synthesis in the plant pathogen ralstonia solanacearum is under the transcriptional control of the master pathogenicity regulator hrpg. this control is exerted essentially on mete expression through the intermediate regulato ...201222615832
sequence diversity in the dickeya flic gene: phylogeny of the dickeya genus and taqman® pcr for 'd. solani', new biovar 3 variant on potato in europe.worldwide, dickeya (formerly erwinia chrysanthemi) is causing soft rot diseases on a large diversity of crops and ornamental plants. strains affecting potato are mainly found in d. dadantii, d. dianthicola and d. zeae, which appear to have a marked geographical distribution. furthermore, a few dickeya isolates from potato are attributed to d. chrysanthemi and d. dieffenbachiae. in europe, isolates of erwinia chrysanthemi biovar 1 and biovar 7 from potato are now classified in d. dianthicola. how ...201222570692
housekeeping gene sequencing and multilocus variable-number tandem-repeat analysis to identify subpopulations within pseudomonas syringae pv. maculicola and pseudomonas syringae pv. tomato that correlate with host specificity.pseudomonas syringae pv. maculicola causes bacterial spot on brassicaceae worldwide, and for the last 10 years severe outbreaks have been reported in the loire valley, france. p. syringae pv. maculicola resembles p. syringae pv. tomato in that it is also pathogenic for tomato and causes the same types of symptoms. we used a collection of 106 strains of p. syringae to characterize the relationships between p. syringae pv. maculicola and related pathovars, paying special attention to p. syringae p ...201222389364
functional and computational analysis of amino acid patterns predictive of type iii secretion system substrates in pseudomonas syringae.bacterial type iii secretion systems (t3sss) deliver proteins called effectors into eukaryotic cells. although n-terminal amino acid sequences are required for translocation, the mechanism of substrate recognition by the t3ss is unknown. almost all actively deployed t3ss substrates in the plant pathogen pseudomonas syringae pathovar tomato strain dc3000 possess characteristic patterns, including (i) greater than 10% serine within the first 50 amino acids, (ii) an aliphatic residue or proline at ...201222558318
sphingolipids and plant defense/disease: the "death" connection and beyond.sphingolipids comprise a major class of structural materials and lipid signaling molecules in all eukaryotic cells. over the past two decades, there has been a phenomenal growth in the study of sphingolipids (i.e., sphingobiology) at an average rate of ∼1000 research articles per year. sphingolipid studies in plants, though accounting for only a small fraction (∼6%) of the total number of publications, have also enjoyed proportionally rapid growth in the past decade. concomitant with the growth ...201222639658
airborne signals from a wounded leaf facilitate viral spreading and induce antibacterial resistance in neighboring plants.many plants release airborne volatile compounds in response to wounding due to pathogenic assault. these compounds serve as plant defenses and are involved in plant signaling. here, we study the effects of pectin methylesterase (pme)-generated methanol release from wounded plants ("emitters") on the defensive reactions of neighboring "receiver" plants. plant leaf wounding resulted in the synthesis of pme and a spike in methanol released into the air. gaseous methanol or vapors from wounded pme-t ...201222496658
cotton ghmkk5 affects disease resistance, induces hr-like cell death, and reduces the tolerance to salt and drought stress in transgenic nicotiana benthamiana.mitogen-activated protein kinase (mapk) cascades are involved in various processes from plant growth and development to biotic and abiotic stress responses. mapk kinases (mapkks), which link mapks and mapkk kinases (mapkkks), play crucial roles in mapk cascades to mediate a variety of stress responses in plants. however, few mapkks have been functionally characterized in cotton (gossypium hirsutum). in this study, a novel gene, ghmkk5, from cotton belonging to the group c mapkks was isolated and ...201222442420
the gpsx gene encoding a glycosyltransferase is important for polysaccharide production and required for full virulence in xanthomonas citri subsp. citri.the gram-negative bacterium xanthomonas citri subsp. citri (xac) causes citrus canker, one of the most destructive diseases of citrus worldwide. in our previous work, a transposon mutant of xac strain 306 with an insertion in the xac3110 locus was isolated in a screening that aimed at identifying genes related to biofilm formation. the xac3110 locus was named as bdp24 for biofilm-defective phenotype and the mutant was observed to be affected in extracellular polysaccharide (eps) and lipopolysacc ...201222404966
the conjugated auxin indole-3-acetic acid-aspartic acid promotes plant disease development.auxin is a pivotal plant hormone that regulates many aspects of plant growth and development. auxin signaling is also known to promote plant disease caused by plant pathogens. however, the mechanism by which this hormone confers susceptibility to pathogens is not well understood. here, we present evidence that fungal and bacterial plant pathogens hijack the host auxin metabolism in arabidopsis thaliana, leading to the accumulation of a conjugated form of the hormone, indole-3-acetic acid (iaa)-a ...201222374398
fructose-bisphophate aldolase exhibits functional roles between carbon metabolism and the hrp system in rice pathogen xanthomonas oryzae pv. oryzicola.fructose-bisphophate aldolase (fbab), is an enzyme in glycolysis and gluconeogenesis in living organisms. the mutagenesis in a unique fbab gene of xanthomonas oryzae pv. oryzicola, the causal agent of rice bacterial leaf streak, led the pathogen not only unable to use pyruvate and malate for growth and delayed its growth when fructose was used as the sole carbon source, but also reduced extracellular polysaccharide (eps) production and impaired bacterial virulence and growth in rice. intriguingl ...201222384086
genetic and genomic approaches for r-gene mediated disease resistance in tomato: retrospects and prospects.tomato (solanum lycopersicum) is one of the world's most important vegetable crops. managing the health of this crop can be particularly challenging; crop resistance may be overcome by new pathogen races while new pathogens have been introduced by global agricultural markets. tomato is extensively used as a model plant for resistance studies and much has been attained through both genetic and biotechnological approaches. in this paper, we illustrate genomic methods currently employed to preserve ...201222350316
a bacterial acetyltransferase destroys plant microtubule networks and blocks secretion.the eukaryotic cytoskeleton is essential for structural support and intracellular transport, and is therefore a common target of animal pathogens. however, no phytopathogenic effector has yet been demonstrated to specifically target the plant cytoskeleton. here we show that the pseudomonas syringae type iii secreted effector hopz1a interacts with tubulin and polymerized microtubules. we demonstrate that hopz1a is an acetyltransferase activated by the eukaryotic co-factor phytic acid. activated h ...201222319451
bacterial effectors target the plant cell nucleus to subvert host transcription.in order to promote virulence, gram-negative bacteria have evolved the ability to inject so-called type iii effector proteins into host cells. the plant cell nucleus appears to be a subcellular compartment repeatedly targeted by bacterial effectors. in agreement with this observation, mounting evidence suggests that manipulation of host transcription is a major strategy developed by bacteria to counteract plant defense responses. it has been suggested that bacterial effectors may adopt at least ...201222353865
arabidopsis thaliana transgenics overexpressing ibr3 show enhanced susceptibility to the bacterium pseudomonas syringae.the gene, indole-3-butyric acid (iba)-response (ibr) 3, is thought to participate in peroxisomal β-oxidation of iba to indole-3-acetic acid. here we show that ibr3 may also play a role in arabidopsis thaliana defence response to microbial pathogens. ibr3 is up-regulated during infection by virulent pseudomonas syringae pv. tomato (pst) dc3000 bacteria. although mutant ibr3-4 did not show a pathogen phenotype, lines overexpressing ibr3 demonstrated enhanced susceptibility to pst dc3000. increased ...201223906045
plant lectin-like antibacterial proteins from phytopathogens pseudomonas syringae and xanthomonas citri.the genomes of pseudomonas syringae pv. syringae 642 and xanthomonas citri pv. malvacearum lmg 761 each carry a putative homologue of the plant lectin-like bacteriocin (llpa) genes previously identified in the rhizosphere isolate pseudomonas putida bw11m1 and the biocontrol strain pseudomonas fluorescens pf-5. the respective purified recombinant proteins, llpapss642 and llpaxcm761 , display genus-specific antibacterial activity across species boundaries. the inhibitory spectrum of the p. syringa ...201223760822
transcriptional profiling of canker-resistant transgenic sweet orange (citrus sinensis osbeck) constitutively overexpressing a spermidine synthase gene.citrus canker disease caused by xanthomonas citri subsp. citri (xcc) is one of the most devastating diseases affecting the citrus industry worldwide. in our previous study, the canker-resistant transgenic sweet orange (citrus sinensis osbeck) plants were produced via constitutively overexpressing a spermidine synthase. to unravel the molecular mechanisms underlying xcc resistance of the transgenic plants, in the present study global transcriptional profiling was compared between untransformed li ...201223509803
transcriptional profiling of canker-resistant transgenic sweet orange (citrus sinensis osbeck) constitutively overexpressing a spermidine synthase gene.citrus canker disease caused by xanthomonas citri subsp. citri (xcc) is one of the most devastating diseases affecting the citrus industry worldwide. in our previous study, the canker-resistant transgenic sweet orange (citrus sinensis osbeck) plants were produced via constitutively overexpressing a spermidine synthase. to unravel the molecular mechanisms underlying xcc resistance of the transgenic plants, in the present study global transcriptional profiling was compared between untransformed li ...201223509803
optimization of the bacterial cytochrome p450 bm3 system for the production of human drug metabolites.drug metabolism in human liver is a process involving many different enzymes. among them, a number of cytochromes p450 isoforms catalyze the oxidation of most of the drugs commercially available. each p450 isoform acts on more than one drug, and one drug may be oxidized by more than one enzyme. as a result, multiple products may be obtained from the same drug, and as the metabolites can be biologically active and may cause adverse drug reactions (adrs), the metabolic profile of a new drug has to ...201223443101
hexanoic acid is a resistance inducer that protects tomato plants against pseudomonas syringae by priming the jasmonic acid and salicylic acid pathways.hexanoic acid-induced resistance (hx-ir) is effective against several pathogens in tomato plants. our study of the mechanisms implicated in hx-ir against pseudomonas syringae pv. tomato dc3000 suggests that hexanoic acid (hx) treatment counteracts the negative effect of coronatine (cor) and jasmonyl-isoleucine (ja-ile) on the salicylic acid (sa) pathway. in hx-treated plants, an increase in the expression of jasmonic acid carboxyl methyltransferase (jmt) and the sa marker genes pr1 and pr5 indic ...201223279078
regulation of cell wall-bound invertase in pepper leaves by xanthomonas campestris pv. vesicatoria type three effectors.xanthomonas campestris pv. vesicatoria (xcv) possess a type 3 secretion system (t3ss) to deliver effector proteins into its solanaceous host plants. these proteins are involved in suppression of plant defense and in reprogramming of plant metabolism to favour bacterial propagation. there is increasing evidence that hexoses contribute to defense responses. they act as substrates for metabolic processes and as metabolic semaphores to regulate gene expression. especially an increase in the apoplast ...201223272161
cloning of a conserved receptor-like protein kinase gene and its use as a functional marker for homoeologous group-2 chromosomes of the triticeae species.receptor-like kinases (rlks) play broad biological roles in plants. we report on a conserved receptor-like protein kinase (rpk) gene from wheat and other triticeae species. the tarpk1 was isolated from the triticum aestivum cv. prins - triticum timopheevii introgression line igvi-465 carrying the powdery mildew resistance gene pm6. the tarpk1 was mapped to homoeologous chromosomes 2a (tarpk1-2a), 2d (tarpk1-2d) and the pm6-carrier chromosome 2g (tarpk1-2g) of igvi-465. under the tested condition ...201223272050
parallel loss-of-function at the rpm1 bacterial resistance locus in arabidopsis thaliana.dimorphism at the resistance to pseudomonas syringae pv. maculicola 1 (rpm1) locus is well documented in natural populations of arabidopsis thaliana and has been portrayed as a long-term balanced polymorphism. the haplotype from resistant plants contains the rpm1 gene, which enables these plants to recognize at least two structurally unrelated bacterial effector proteins (avrb and avrrpm1) from bacterial crop pathogens. a complete deletion of the rpm1 coding sequence has been interpreted as a si ...201223272006
the role of canonical and noncanonical pre-mrna splicing in plant stress responses.plants are sessile organisms capable of adapting to various environmental constraints, such as high or low temperatures, drought, soil salinity, or pathogen attack. to survive the unfavorable conditions, plants actively employ pre-mrna splicing as a mechanism to regulate expression of stress-responsive genes and reprogram intracellular regulatory networks. there is a growing evidence that various stresses strongly affect the frequency and diversity of alternative splicing events in the stress-re ...201223509698
the role of canonical and noncanonical pre-mrna splicing in plant stress responses.plants are sessile organisms capable of adapting to various environmental constraints, such as high or low temperatures, drought, soil salinity, or pathogen attack. to survive the unfavorable conditions, plants actively employ pre-mrna splicing as a mechanism to regulate expression of stress-responsive genes and reprogram intracellular regulatory networks. there is a growing evidence that various stresses strongly affect the frequency and diversity of alternative splicing events in the stress-re ...201223509698
a role in immunity for arabidopsis cysteine protease rd21, the ortholog of the tomato immune protease c14.secreted papain-like cys proteases are important players in plant immunity. we previously reported that the c14 protease of tomato is targeted by cystatin-like epic proteins that are secreted by the oomycete pathogen phytophthora infestans (pinf) during infection. c14 has been under diversifying selection in wild potato species coevolving with pinf and reduced c14 levels result in enhanced susceptibility for pinf. here, we investigated the role c14-epic-like interactions in the natural pathosyst ...201222238602
slya regulates t3ss genes in parallel with the t3ss master regulator hrpl in dickeya dadantii 3937.the hrp (hypersensitive response and pathogenicity) genes of dickeya dadantii 3937 encode a type iii secretion system (t3ss) which is essential for its full virulence. previous studies of the t3ss regulation in d. dadantii 3937 revealed that the expression of the hrp genes is regulated by a master regulator hrpl through the hrpx-hrpy-hrps-hrpl and gacs-gaca-rsmb-rsma pathways. in this work, we identified a novel regulator of the slya/marr family, slya, which regulates hrp genes of the hrpl regul ...201222267675
arabidopsis histidine kinase 5 regulates salt sensitivity and resistance against bacterial and fungal infection.• the ability of plants to adapt to multiple stresses imposed by the natural environment requires cross-talk and fine-tuning of stress signalling pathways. the hybrid histidine kinase arabidopsis histidine kinase 5 (ahk5) is known to mediate stomatal responses to exogenous and endogenous signals in arabidopsis thaliana. the purpose of this study was to determine whether the function of ahk5 in stress signalling extends beyond stomatal responses. • plant growth responses to abiotic stresses, tiss ...201222256998
environmental factors affecting the expression of pilab as well as the proteome and transcriptome of the grass endophyte azoarcus sp. strain bh72.bacterial communication is involved in regulation of cellular mechanisms such as metabolic processes, microbe-host interactions or biofilm formation. in the nitrogen-fixing model endophyte of grasses azoarcus sp. strain bh72, known cell-cell signaling systems have not been identified; however, the pila gene encoding the structural protein of type iv pili that are essential for plant colonization appears to be regulated in a population density-dependent manner.201222276194
stenotrophomonas maltophilia: an emerging global opportunistic pathogen.summary: stenotrophomonas maltophilia is an emerging multidrug-resistant global opportunistic pathogen. the increasing incidence of nosocomial and community-acquired s. maltophilia infections is of particular concern for immunocompromised individuals, as this bacterial pathogen is associated with a significant fatality/case ratio. s. maltophilia is an environmental bacterium found in aqueous habitats, including plant rhizospheres, animals, foods, and water sources. infections of s. maltophilia c ...201222232370
variation in local carrying capacity and the individual fate of bacterial colonizers in the phyllosphere.using a phyllosphere model system, we demonstrated that the term 'carrying capacity', as it is commonly used in microbial ecology, needs to be understood as the sum of many 'local carrying capacities' in order to better explain and predict the course and outcome of bacterial colonization of an environment. using a green fluorescent protein-based bioreporter system for the quantification of reproductive success (rs) in individual erwinia herbicola cells, we were able to reconstruct the contributi ...201222258099
broad-spectrum acquired resistance in barley induced by the pseudomonas pathosystem shares transcriptional components with arabidopsis sar.inducible resistance responses play a central role in the defence of plants against pathogen attack. acquired resistance (ar) is induced alongside defence towards primary attack, providing broad-spectrum protection against subsequent pathogen challenge. the localisation and molecular basis of ar in cereals is poorly understood, in contrast with the well-characterised systemic acquired resistance (sar) response in arabidopsis. here, we use pseudomonas syringae as a biological inducer of ar in bar ...201222250583
hopas1 recognition significantly contributes to arabidopsis nonhost resistance to pseudomonas syringae pathogens.• plant immunity is activated by sensing either conserved microbial signatures, called pathogen/microbe-associated molecular patterns (p/mamps), or specific effectors secreted by pathogens. however, it is not known why most microbes are nonpathogenic in most plant species. • nonhost resistance (nhr) consists of multiple layers of innate immunity and protects plants from the vast majority of potentially pathogenic microbes. effector-triggered immunity (eti) has been implicated in race-specific di ...201222053875
Two small RNAs, CrcY and CrcZ, act in concert to sequester the Crc global regulator in Pseudomonas putida, modulating catabolite repression.The Crc protein is a translational repressor that recognizes a specific target at some mRNAs, controlling catabolite repression and co-ordinating carbon metabolism in pseudomonads. In Pseudomonas aeruginosa, the levels of free Crc protein are controlled by CrcZ, a sRNA that sequesters Crc, acting as an antagonist. We show that, in Pseudomonas putida, the levels of free Crc are controlled by CrcZ and by a novel 368 nt sRNA named CrcY. CrcZ and CrcY, which contain six potential targets for Crc, we ...201222053874
Conserved Structural Mechanisms for Autoinhibition in IpaH Ubiquitin Ligases.The IpaH family of novel E3 ligase (NEL) enzymes occur in a variety of pathogenic and commensal bacteria that interact with eukaryotic hosts. We demonstrate that the leucine-rich repeat (LRR) substrate recognition domains of different IpaH enzymes autoinhibit the enzymatic activity of the adjacent catalytic novel E3 ligase domain by two distinct but conserved structural mechanisms. Autoinhibition is required for the in vivo biological activity of two IpaH enzymes in a eukaryotic model system. Au ...201222065585
Conserved Structural Mechanisms for Autoinhibition in IpaH Ubiquitin Ligases.The IpaH family of novel E3 ligase (NEL) enzymes occur in a variety of pathogenic and commensal bacteria that interact with eukaryotic hosts. We demonstrate that the leucine-rich repeat (LRR) substrate recognition domains of different IpaH enzymes autoinhibit the enzymatic activity of the adjacent catalytic novel E3 ligase domain by two distinct but conserved structural mechanisms. Autoinhibition is required for the in vivo biological activity of two IpaH enzymes in a eukaryotic model system. Au ...201222065585
Proteomic analysis of colony morphology variants of Burkholderia pseudomallei defines a role for the arginine deiminase system in bacterial survival.Colony morphology variation of Burkholderia pseudomallei is a notable feature of a proportion of primary clinical cultures from patients with melioidosis. Here, we examined the hypothesis that colony morphology switching results in phenotypic changes associated with enhanced survival under adverse conditions. We generated isogenic colony morphology types II and III from B. pseudomallei strain 153 type I, and compared their protein expression profiles using 2D gel electrophoresis. Numerous protei ...201222062159
Ethylene-Responsive Element-Binding Factor 5, ERF5, Is Involved in Chitin-Induced Innate Immunity Response.Our recent work demonstrated that chitin treatment modulated the expression of 118 transcription factor (TF) genes in Arabidopsis. To investigate the potential roles of these TF in chitin signaling and plant defense, we initiated an interaction study among these TF proteins, as well as two chitin-activated mitogen-activated protein kinases (MPK3 and MPK6), using a yeast two-hybrid system. This study revealed interactions among the following proteins: three ethylene-responsive element-binding fac ...201221936663
contribution of siderophore systems to growth and urinary tract colonization of asymptomatic bacteriuria escherichia coli.the molecular mechanisms that define asymptomatic bacteriuria (abu) escherichia coli colonization of the human urinary tract remain to be properly elucidated. here, we utilize abu e. coli strain 83972 as a model to dissect the contribution of siderophores to iron acquisition, growth, fitness, and colonization of the urinary tract. we show that e. coli 83972 produces enterobactin, salmochelin, aerobactin, and yersiniabactin and examine the role of these systems using mutants defective in sideroph ...201221930757
mRNA context dependent regulation of cytotoxic necrotizing factor 1 translation by GidA, a tRNA modification enzyme in Escherichia coli.Cytotoxic necrotizing factor 1 (CNF1), the paradigm of Rho GTPase activating bacterial toxins has been shown to promote E. coli invasion of human brain microvascular endothelial cells (HBMEC), which constitute the blood-brain barrier, but its synthesis and secretion is unclear. In this study, we performed mini Tn5 mutagenesis screen to identify genetic requirements for CNF1 production and secretion. Transposon mutagenesis screen of meningitis-causing E. coli K1 strain RS218 revealed that CNF1 pr ...201222020226
mRNA context dependent regulation of cytotoxic necrotizing factor 1 translation by GidA, a tRNA modification enzyme in Escherichia coli.Cytotoxic necrotizing factor 1 (CNF1), the paradigm of Rho GTPase activating bacterial toxins has been shown to promote E. coli invasion of human brain microvascular endothelial cells (HBMEC), which constitute the blood-brain barrier, but its synthesis and secretion is unclear. In this study, we performed mini Tn5 mutagenesis screen to identify genetic requirements for CNF1 production and secretion. Transposon mutagenesis screen of meningitis-causing E. coli K1 strain RS218 revealed that CNF1 pr ...201222020226
The Arabidopsis short-chain dehydrogenase/reductase 3, an ABSCISIC ACID DEFICIENT 2 homolog, is involved in plant defense responses but not in ABA biosynthesis.ABSCISIC ACID DEFICIENT2 (ABA2) encodes a short-chain dehydrogenase/reductase1 (SDR1) that catalyzes the multi-step conversion of xanthoxin to abscisic aldehyde during abscisic acid (ABA) biosynthesis in Arabidopsis thaliana. In this study, AtSDR2 and AtSDR3, the two closest homologs to AtABA2, were investigated for their potential role in ABA biosynthesis. AtSDR2 showed undetectable transcription in plants grown under normal conditions or under stress. AtSDR3 and AtABA2 have different spatial a ...201222153241
high-throughput analysis of growth differences among phage strains.although methods such as spectrophotometry are useful for identifying growth differences among bacterial strains, it is currently difficult to similarly determine whether bacteriophage strains differ in growth using high throughput methods. here we use automated spectrophotometry to develop an in vitro method for indirectly distinguishing fitness (growth) differences among virus strains, based on direct measures of their infected bacterial hosts. we used computer simulations of a mathematical mo ...201222101310
a tomato lysm receptor-like kinase promotes immunity and its kinase activity is inhibited by avrptob.resistance in tomato (solanum lycopersicum) to infection by pseudomonas syringae involves both detection of pathogen-associated molecular patterns (pamps) and recognition by the host pto kinase of pathogen effector avrptob which is translocated into the host cell and interferes with pamp-triggered immunity (pti). the n-terminal portion of avrptob is sufficient for its virulence activity and for recognition by pto. an amino acid substitution in avrptob, f173a, abolishes these activities. to inves ...201221880077
a tomato lysm receptor-like kinase promotes immunity and its kinase activity is inhibited by avrptob.resistance in tomato (solanum lycopersicum) to infection by pseudomonas syringae involves both detection of pathogen-associated molecular patterns (pamps) and recognition by the host pto kinase of pathogen effector avrptob which is translocated into the host cell and interferes with pamp-triggered immunity (pti). the n-terminal portion of avrptob is sufficient for its virulence activity and for recognition by pto. an amino acid substitution in avrptob, f173a, abolishes these activities. to inves ...201221880077
HrpZ harpins from different Pseudomonas syringae pathovars differ in molecular interactions and in induction of anion channel responses in Arabidopsis thaliana suspension cells.HrpZ, a type three secretion system helper protein from the plant-pathogen Pseudomonas syringae, can be recognized by many plants as a defence elicitor. Responses of Arabidopsis thaliana suspension cells to different HrpZ variants were studied by electrophysiological methods and cell death assay. Purified HrpZ originating from a compatible pathogen P. syringae pv. tomato DC3000 (HrpZ(Pto)) and incompatible P. syringae pv. phaseolicola (HrpZ(Pph)) both promoted Arabidopsis cell death. As an early ...201222153254
Syringolin B-inspired proteasome inhibitor analogue TIR-203 exhibits enhanced biological activity in multiple myeloma and neuroblastoma.Context: The bacterium Pseudomonas syringae pv. syringae (Pss) is a pathogen of many plant species and causes, for example, brown spot disease in bean plants (Phaseolus vulgaris). Pss excretes the syringolins, natural product molecules that act as a virulence factors and inhibit the proteasome of the host plants. Objective: Proteasome inhibitors belong to an important class of anticancer agents and bortezomib (Velcade(®)) has been Food and Drug Administration-approved for the treatment of mult ...201222196580
genome sequence of azospirillum brasilense cbg497 and comparative analyses of azospirillum core and accessory genomes provide insight into niche adaptation.bacteria of the genus azospirillum colonize roots of important cereals and grasses, and promote plant growth by several mechanisms, notably phytohormone synthesis. the genomes of several azospirillum strains belonging to different species, isolated from various host plants and locations, were recently sequenced and published. in this study, an additional genome of an a. brasilense strain, isolated from maize grown on an alkaline soil in the northeast of mexico, strain cbg497, was obtained. compa ...201224705077
plant growth-promoting bacteria: mechanisms and applications.the worldwide increases in both environmental damage and human population pressure have the unfortunate consequence that global food production may soon become insufficient to feed all of the world's people. it is therefore essential that agricultural productivity be significantly increased within the next few decades. to this end, agricultural practice is moving toward a more sustainable and environmentally friendly approach. this includes both the increasing use of transgenic plants and plant ...201224278762
cellular function and molecular structure of ecto-nucleotidases.ecto-nucleotidases play a pivotal role in purinergic signal transmission. they hydrolyze extracellular nucleotides and thus can control their availability at purinergic p2 receptors. they generate extracellular nucleosides for cellular reuptake and salvage via nucleoside transporters of the plasma membrane. the extracellular adenosine formed acts as an agonist of purinergic p1 receptors. they also can produce and hydrolyze extracellular inorganic pyrophosphate that is of major relevance in the c ...201222555564
characterization of nitric oxide-inducing lipid a derived from mesorhizobium loti lipopolysaccharide.mesorhizobium loti is a member of the rhizobia and forms nitrogen-fixing symbioses with several lotus species. recently, it was reported that m. loti bacterial cells and their lipopolysaccharide (lps) preparations transiently induced nitric oxide (no) production in the roots of l. japonicus. we subsequently found that polysaccharides and the lipid a moiety were responsible for this no induction. in this study, we elucidated the chemical structure of m. loti lipid a and characterized its no-induc ...201223059724
the effect of iron limitation on the transcriptome and proteome of pseudomonas fluorescens pf-5.one of the most important micronutrients for bacterial growth is iron, whose bioavailability in soil is limited. consequently, rhizospheric bacteria such as pseudomonas fluorescens employ a range of mechanisms to acquire or compete for iron. we investigated the transcriptomic and proteomic effects of iron limitation on p. fluorescens pf-5 by employing microarray and itraq techniques, respectively. analysis of this data revealed that genes encoding functions related to iron homeostasis, including ...201222723948
iodide oxidation by a novel multicopper oxidase from the alphaproteobacterium strain q-1.alphaproteobacterium strain q-1 is able to oxidize iodide (i(-)) to molecular iodine (i(2)) by an oxidase-like enzyme. one of the two isoforms of the iodide-oxidizing enzyme (ioe-ii) produced by this strain was excised from a native polyacrylamide gel, eluted, and purified. ioe-ii appeared as a single band (51 kda) and showed significant in-gel iodide-oxidizing activity in sodium dodecyl sulfate-polyacrylamide gel electrophoresis without heat treatment. however, at least two bands with much high ...201222447601
comparative transcriptional analysis of homologous pathogenic and non-pathogenic lawsonia intracellularis isolates in infected porcine cells.lawsonia intracellularis is the causative agent of proliferative enteropathy. this disease affects various animal species, including nonhuman primates, has been endemic in pigs, and is an emerging concern in horses. non-pathogenic variants obtained through multiple passages in vitro do not induce disease, but bacterial isolates at low passage induce clinical and pathological changes. we hypothesize that genes differentially expressed between pathogenic (passage 10) and non-pathogenic (passage 60 ...201223056413
reproductive clonality of pathogens: a perspective on pathogenic viruses, bacteria, fungi, and parasitic protozoa.we propose that clonal evolution in micropathogens be defined as restrained recombination on an evolutionary scale, with genetic exchange scarce enough to not break the prevalent pattern of clonal population structure, a definition already widely used for all kinds of pathogens, although not clearly formulated by many scientists and rejected by others. the two main manifestations of clonal evolution are strong linkage disequilibrium (ld) and widespread genetic clustering ("near-clading"). we hyp ...201222949662
bactquant: an enhanced broad-coverage bacterial quantitative real-time pcr assay.bacterial load quantification is a critical component of bacterial community analysis, but a culture-independent method capable of detecting and quantifying diverse bacteria is needed. based on our analysis of a diverse collection of 16 s rrna gene sequences, we designed a broad-coverage quantitative real-time pcr (qpcr) assay--bactquant--for quantifying 16 s rrna gene copy number and estimating bacterial load. we further utilized in silico evaluation to complement laboratory-based qpcr characte ...201222510143
different biosynthetic pathways to fosfomycin in pseudomonas syringae and streptomyces species.fosfomycin is a wide-spectrum antibiotic that is used clinically to treat acute cystitis in the united states. the compound is produced by several strains of streptomycetes and pseudomonads. we sequenced the biosynthetic gene cluster responsible for fosfomycin production in pseudomonas syringae pb-5123. surprisingly, the biosynthetic pathway in this organism is very different from that in streptomyces fradiae and streptomyces wedmorensis. the pathways share the first and last steps, involving co ...201222615277
comparative analysis of two phenotypically-similar but genomically-distinct burkholderia cenocepacia-specific bacteriophages.genomic analysis of bacteriophages infecting the burkholderia cepacia complex (bcc) is an important preliminary step in the development of a phage therapy protocol for these opportunistic pathogens. the objective of this study was to characterize kl1 (vb_bces_kl1) and ah2 (vb_bces_ah2), two novel burkholderia cenocepacia-specific siphoviruses isolated from environmental samples.201222676492
polymorphic toxin systems: comprehensive characterization of trafficking modes, processing, mechanisms of action, immunity and ecology using comparative genomics.proteinaceous toxins are observed across all levels of inter-organismal and intra-genomic conflicts. these include recently discovered prokaryotic polymorphic toxin systems implicated in intra-specific conflicts. they are characterized by a remarkable diversity of c-terminal toxin domains generated by recombination with standalone toxin-coding cassettes. prior analysis revealed a striking diversity of nuclease and deaminase domains among the toxin modules. we systematically investigated polymorp ...201222731697
fluoride resistance and transport by riboswitch-controlled clc antiporters.a subclass of bacterial clc anion-transporting proteins, phylogenetically distant from long-studied clcs, was recently shown to be specifically up-regulated by f(-). we establish here that a set of randomly selected representatives from this "clc(f)" clade protect escherichia coli from f(-) toxicity, and that the purified proteins catalyze transport of f(-) in liposomes. sequence alignments and membrane transport experiments using (19)f nmr, osmotic response assays, and planar lipid bilayer reco ...201222949689
integrating conjugative elements as vectors of antibiotic, mercury, and quaternary ammonium compound resistance in marine aquaculture environments.the presence of sxt/r391-related integrating conjugative elements (ices) in bacterial strains isolated from fish obtained from marine aquaculture environments in 2001 to 2010 in the northwestern iberian peninsula was studied. ices were detected in 12 strains taxonomically related to vibrio scophthalmi (3 strains), vibrio splendidus (5 strains), vibrio alginolyticus (1 strain), shewanella haliotis (1 strain), and enterovibrio nigricans (2 strains), broadening the known host range able to harbor s ...201222314526
bioinformatic characterization of the 4-toluene sulfonate uptake permease (tsup) family of transmembrane proteins.the ubiquitous sequence diverse 4-toluene sulfonate uptake permease (tsup) family contains few characterized members and is believed to catalyze the transport of several sulfur-based compounds. prokaryotic members of the tsup family outnumber the eukaryotic members substantially, and in prokaryotes, but not eukaryotes, extensive lateral gene transfer occurred during family evolution. despite unequal representation, homologues from the three taxonomic domains of life share well-conserved motifs. ...201222192777
bioinformatic characterization of the 4-toluene sulfonate uptake permease (tsup) family of transmembrane proteins.the ubiquitous sequence diverse 4-toluene sulfonate uptake permease (tsup) family contains few characterized members and is believed to catalyze the transport of several sulfur-based compounds. prokaryotic members of the tsup family outnumber the eukaryotic members substantially, and in prokaryotes, but not eukaryotes, extensive lateral gene transfer occurred during family evolution. despite unequal representation, homologues from the three taxonomic domains of life share well-conserved motifs. ...201222192777
Transcript and metabolite analysis of the Trichoderma-induced systemic resistance response to Pseudomonas syringae in Arabidopsis thaliana.In the present study we have assessed, by transcriptional and metabolic profiling, the systemic defence response of Arabidopsis thaliana plants to the leaf pathogen Pseudomonas syringae pv. tomato DC3000 (Pst) induced by the beneficial fungus Trichoderma asperelloides T203. Expression analysis (qPCR) of a set of 137 Arabidopsis genes related to Pst defence responses showed that T203 root colonization is not associated with major detectable transcriptomic changes in leaves. However, plants challe ...201221852347
E622, a miniature, virulence-associated mobile element.Miniature inverted terminal repeat elements (MITEs) are nonautonomous mobile elements that have a significant impact on bacterial evolution. Here we characterize E622, a 611-bp virulence-associated MITE from Pseudomonas syringae, which contains no coding region but has almost perfect 168-bp inverted repeats. Using an antibiotic coupling assay, we show that E622 is transposable and can mobilize an antibiotic resistance gene contained between its borders. Its predicted parent element, designated T ...201222081398
cj1386 is an ankyrin-containing protein involved in heme trafficking to catalase in campylobacter jejuni.campylobacter jejuni, a microaerophilic bacterium, is the most frequent cause of human bacterial gastroenteritis. c. jejuni is exposed to harmful reactive oxygen species (ros) produced during its own normal metabolic processes and during infection from the host immune system and from host intestinal microbiota. these ros will damage dna and proteins and cause peroxidation of lipids. consequently, identifying ros defense mechanisms is important for understanding how campylobacter survives this en ...201222081390
duplex quantitative real-time pcr assay for the detection and discrimination of the eggs of toxocara canis and toxocara cati (nematoda, ascaridoidea) in soil and fecal samples.toxocarosis is a zoonotic disease caused by toxocara canis (t. canis) and/or toxocara cati (t. cati), two worldwide distributed roundworms which are parasites of canids and felids, respectively. infections of humans occur through ingestion of embryonated eggs of t. canis or t. cati, when playing with soils contaminated with dogs or cats feces. accordingly, the assessment of potential contamination of these areas with these roundworms eggs is paramount.201223216873
signal molecules mediate the impact of the earthworm aporrectodea caliginosa on growth, development and defence of the plant arabidopsis thaliana.earthworms have generally a positive impact on plant growth, which is often attributed to a trophic mechanism: namely, earthworms increase the release of mineral nutrients from soil litter and organic matter. an alternative hypothesis has been proposed since the discovery of a signal molecule (indole acetic acid) in earthworm faeces. in this study, we used methodologies developed in plant science to gain information on ecological mechanisms involved in plant-earthworm interaction, by looking at ...201223226498
ethylene in mutualistic symbioses.ethylene (et) is a gaseous phytohormone that participates in various plant physiological processes and essentially contributes to plant immunity. et conducts its functions by regulating the expression of et-responsive genes or in crosstalk with other hormones. several recent studies have shown the significance of et in the establishment and development of plant-microbe interactions. therefore, it is not surprising that pathogens and mutualistic symbionts target et synthesis or signaling to colon ...201223072986
induced resistance by a long-chain bacterial volatile: elicitation of plant systemic defense by a c13 volatile produced by paenibacillus polymyxa.some strains of plant growth-promoting rhizobacteria (pgpr) elicit induced systemic resistance (isr) by emission of volatile organic compounds (vocs) including short chain alcohols, acetoin, and 2,3-butanediol. the objective of this study was to evaluate whether species-specific vocs from pgpr strain paenibacillus polymyxa e681 can promote growth and induce resistance in arabidopsis.201223209558
small rnas and their role in biofilm formation.the formation of biofilms is initiated by bacteria transitioning from the planktonic to the surface-associated mode of growth. several regulatory systems have been described to govern the initiation and subsequent formation of biofilms. recent evidence suggests that regulatory networks governing the decision of bacteria whether to attach and form biofilms or remain as planktonic cells are further subject to regulation by small non-coding rnas (srnas). this is accomplished by srnas fine-tuning re ...201223178000
small rnas and their role in biofilm formation.the formation of biofilms is initiated by bacteria transitioning from the planktonic to the surface-associated mode of growth. several regulatory systems have been described to govern the initiation and subsequent formation of biofilms. recent evidence suggests that regulatory networks governing the decision of bacteria whether to attach and form biofilms or remain as planktonic cells are further subject to regulation by small non-coding rnas (srnas). this is accomplished by srnas fine-tuning re ...201223178000
assessment of the relevance of the antibiotic 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine from pantoea agglomerans biological control strains against bacterial plant pathogens.the epiphyte pantoea agglomerans 48b/90 (pa48b) is a promising biocontrol strain against economically important bacterial pathogens such as erwinia amylovora. strain pa48b produces the broad-spectrum antibiotic 2-amino-3-(oxirane-2,3-dicarboxamido)-propanoyl-valine (apv) in a temperature-dependent manner. an apv-negative mutant still suppressed the e. amylovora population and fire blight disease symptoms in apple blossom experiments under greenhouse conditions, but was inferior to the pa48b wild ...201223233458
synthase-dependent exopolysaccharide secretion in gram-negative bacteria.the biosynthesis and export of bacterial cell-surface polysaccharides is known to occur through several distinct mechanisms. recent advances in the biochemistry and structural biology of several proteins in synthase-dependent polysaccharide secretion systems have identified key conserved components of this pathway in gram-negative bacteria. these components include an inner-membrane-embedded polysaccharide synthase, a periplasmic tetratricopeptide repeat (tpr)-containing scaffold protein, and an ...201223117123
synthase-dependent exopolysaccharide secretion in gram-negative bacteria.the biosynthesis and export of bacterial cell-surface polysaccharides is known to occur through several distinct mechanisms. recent advances in the biochemistry and structural biology of several proteins in synthase-dependent polysaccharide secretion systems have identified key conserved components of this pathway in gram-negative bacteria. these components include an inner-membrane-embedded polysaccharide synthase, a periplasmic tetratricopeptide repeat (tpr)-containing scaffold protein, and an ...201223117123
metabolic and transcriptomic changes induced in arabidopsis by the rhizobacterium pseudomonas fluorescens ss101.systemic resistance induced in plants by nonpathogenic rhizobacteria is typically effective against multiple pathogens. here, we show that root-colonizing pseudomonas fluorescens strain ss101 (pf.ss101) enhanced resistance in arabidopsis (arabidopsis thaliana) against several bacterial pathogens, including pseudomonas syringae pv tomato (pst) and the insect pest spodoptera exigua. transcriptomic analysis and bioassays with specific arabidopsis mutants revealed that, unlike many other rhizobacter ...201223073694
characterization of bacteria associated with pinewood nematode bursaphelenchus xylophilus.pine wilt disease (pwd) is a complex disease integrating three major agents: the pathogenic agent, the pinewood nematode bursaphelenchus xylophilus; the insect-vector monochamus spp.; and the host pine tree, pinus sp. since the early 80's, the notion that another pathogenic agent, namely bacteria, may play a role in pwd has been gaining traction, however the role of bacteria in pwd is still unknown. the present work supports the possibility that some b. xylophilus-associated bacteria may play a ...201223091599
methylobacterium-induced endophyte community changes correspond with protection of plants against pathogen attack.plant inoculation with endophytic bacteria that normally live inside the plant without harming the host is a highly promising approach for biological disease control. the mechanism of resistance induction by beneficial bacteria is poorly understood, because pathways are only partly known and systemic responses are typically not seen. the innate endophytic community structures change in response to external factors such as inoculation, and bacterial endophytes can exhibit direct or indirect antag ...201223056459
fatty acid biosynthesis in pseudomonas aeruginosa is initiated by the faby class of β-ketoacyl acyl carrier protein synthases.the prototypical type ii fatty acid synthesis (fas) pathway in bacteria utilizes two distinct classes of β-ketoacyl synthase (kas) domains to assemble long-chain fatty acids, the kasiii domain for initiation and the kasi/ii domain for elongation. the central role of fas in bacterial viability and virulence has stimulated significant effort toward developing kas inhibitors, particularly against the kasiii domain of the β-acetoacetyl-acyl carrier protein (acp) synthase fabh. herein, we show that t ...201222753059
virulence of the pseudomonas fluorescens clinical strain mfn1032 towards dictyostelium discoideum and macrophages in relation with type iii secretion system.pseudomonas fluorescens biovar i mfn1032 is a clinical isolate able to grow at 37°c. this strain displays secretion-mediated hemolytic activity involving phospholipase c and cyclolipopeptides, and a cell-associated hemolytic activity distinct from the secreted hemolytic activity. cell-associated hemolysis is independent of biosurfactant production and remains in a gaca mutant. disruption of the hrpu-like operon (the basal part of type iii secretion system from rhizospheric strains) suppresses th ...201223020706
new secreted toxins and immunity proteins encoded within the type vi secretion system gene cluster of serratia marcescens.protein secretion systems are critical to bacterial virulence and interactions with other organisms. the type vi secretion system (t6ss) is found in many bacterial species and is used to target either eukaryotic cells or competitor bacteria. however, t6ss-secreted proteins have proven surprisingly elusive. here, we identified two secreted substrates of the antibacterial t6ss from the opportunistic human pathogen, serratia marcescens. ssp1 and ssp2, both encoded within the t6ss gene cluster, were ...201222957938
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