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characterization of the rna degradosome of pseudoalteromonas haloplanktis: conservation of the rnase e-rhlb interaction in the gammaproteobacteria.the degradosome is a multienzyme complex involved in mrna degradation in escherichia coli. the essential endoribonuclease rnase e contains a large noncatalytic region necessary for protein-protein interactions with other components of the rna degradosome. interacting proteins include the dead-box rna helicase rhlb, the glycolytic enzyme enolase, and the exoribonuclease pnpase. pseudoalteromonas haloplanktis, a psychrotolerant gammaproteobacterium distantly related to e. coli, encodes homologs of ...201020729366
molecular cloning and characterization of a novel tomato xylosyltransferase specific for gentisic acid.the importance of salicylic acid (sa) in the signal transduction pathway of plant disease resistance has been well documented in many incompatible plant-pathogen interactions, but less is known about signalling in compatible interactions. in this type of interaction, tomato plants have been found to accumulate high levels of 2,5-dihydroxybenzoic acid (gentisic acid, ga), a metabolic derivative of sa. exogenous ga treatments induce in tomato plants a set of pr proteins that differ from those indu ...201020729481
pseudomonas syringae infection triggers de novo synthesis of phytosphingosine from sphinganine in arabidopsis thaliana.sphingolipids are important membrane components and also regulate cell proliferation and apoptosis. we detected a fast increase of the free sphingobase t18:0 (phytosphinganine) in arabidopsis leaves after inoculation with an avirulent strain of the bacterial pathogen pseudomonas syringae pathovar tomato, characterized by host cell death reactions. the induction of phytosphinganine was more transient in virulent interactions lacking cell death reactions, suggesting a positive role of t18:0 in the ...201020732322
quinolones: from antibiotics to autoinducers.since quinine was first isolated, animals, plants and microorganisms producing a wide variety of quinolone compounds have been discovered, several of which possess medicinally interesting properties ranging from antiallergenic and anticancer to antimicrobial activities. over the years, these have served in the development of many synthetic drugs, including the successful fluoroquinolone antibiotics. pseudomonas aeruginosa and related bacteria produce a number of 2-alkyl-4(1h)-quinolones, some of ...201120738404
quinolones: from antibiotics to autoinducers.since quinine was first isolated, animals, plants and microorganisms producing a wide variety of quinolone compounds have been discovered, several of which possess medicinally interesting properties ranging from antiallergenic and anticancer to antimicrobial activities. over the years, these have served in the development of many synthetic drugs, including the successful fluoroquinolone antibiotics. pseudomonas aeruginosa and related bacteria produce a number of 2-alkyl-4(1h)-quinolones, some of ...201120738404
overexpression of ahl20 negatively regulates defenses in arabidopsis.plants are equipped to recognize invading pathogenic microbes and activate innate immune responses by sensing pathogen-associated molecular patterns (pamps). pamp-triggered immunity (pti) is critical for plant resistance to potential pathogens. although the mechanism by which pti is activated has been intensively studied, exactly how plants prevent unregulated immune responses is less well understood. here we provide evidence that ahl20, an at-hook containing dna-binding protein, negatively regu ...201020738724
comparative genomics and functional analysis of niche-specific adaptation in pseudomonas putida.pseudomonas putida is a gram-negative rod-shaped gammaproteobacterium that is found throughout various environments. members of the species p. putida show a diverse spectrum of metabolic activities, which is indicative of their adaptation to various niches, which includes the ability to live in soils and sediments contaminated with high concentrations of heavy metals and organic contaminants. pseudomonas putida strains are also found as plant growth-promoting rhizospheric and endophytic bacteria ...201120796030
comparative genomics and functional analysis of niche-specific adaptation in pseudomonas putida.pseudomonas putida is a gram-negative rod-shaped gammaproteobacterium that is found throughout various environments. members of the species p. putida show a diverse spectrum of metabolic activities, which is indicative of their adaptation to various niches, which includes the ability to live in soils and sediments contaminated with high concentrations of heavy metals and organic contaminants. pseudomonas putida strains are also found as plant growth-promoting rhizospheric and endophytic bacteria ...201120796030
inferring the evolutionary history of the plant pathogen pseudomonas syringae from its biogeography in headwaters of rivers in north america, europe, and new zealand.nonhost environmental reservoirs of pathogens play key roles in their evolutionary ecology and in particular in the evolution of pathogenicity. in light of recent reports of the plant pathogen pseudomonas syringae in pristine waters outside agricultural regions and its dissemination via the water cycle, we have examined the genetic and phenotypic diversity, population structure, and biogeography of p. syringae from headwaters of rivers on three continents and their phylogenetic relationship to s ...201020802828
abc transporters involved in export of cell surface glycoconjugates.complex glycoconjugates play critical roles in the biology of microorganisms. despite the remarkable diversity in glycan structures and the bacteria that produce them, conserved themes are evident in the biosynthesis-export pathways. one of the primary pathways involves representatives of the atp-binding cassette (abc) transporter superfamily. these proteins are responsible for the export of a wide variety of cell surface oligo- and polysaccharides in both gram-positive and gram-negative bacteri ...201020805402
genomics of fungal disease resistance in tomato.tomato (solanum lycopersicum) is an important vegetable crop worldwide. often times, its production is hindered by fungal diseases. important fungal diseases limiting tomato production are late blight, caused by phytophthora infestans, early blight, caused by alternaria solanii, and septoria leaf spot, caused by septoria lycopersici, fusarium wilt caused by fusarium oxysporium fsp. oxysporium, and verticilium wilt caused by verticilium dahlea. the phytophthora infestans is the same fungus that c ...201020808521
[absence of mutagenic effect of pseudomonas syringae pv. atrofaciens 9400 and pantoea agglomerans p324 culture liquids].the mutagenic activity of the culture liquids of phytopathogenic strain pseudomonas syringae pv. atrofaciens 9400 and epiphytic strain pantoea agglomerans p324 was studied in the ames test and allium cepa-test. in pro- and eucariotic test-systems no effect of the culture liquids of these bacteria on spontaneous mutations of salmonella typhimurium ta98 and ta100 or chromosome aberrations in the cells of allium cepa root apical meristem was found.201020812509
lipidation by the host prenyltransferase machinery facilitates membrane localization of legionella pneumophila effector proteins.the intracellular human pathogen legionella pneumophila translocates multiple proteins in the host cytosol known as effectors, which subvert host cellular processes to create a membrane-bound organelle that supports bacterial replication. it was observed that several legionella effectors encode a prototypical eukaryotic prenylation caax motif (where c represents a cysteine residue and a denotes an aliphatic amino acid). these bacterial motifs mediated posttranslational modification of effector p ...201020813839
fibrillin4 is required for plastoglobule development and stress resistance in apple and arabidopsis.the fibrillins are a large family of chloroplast proteins that have been linked with stress tolerance and disease resistance. fibrillin4 (fib4) is found associated with the photosystem ii light-harvesting complex, thylakoids, and plastoglobules, which are chloroplast compartments rich in lipophilic antioxidants. for this study, fib4 expression was knocked down in apple (malus 3 domestica) using rna interference. plastoglobule osmiophilicity was decreased in fib4 knockdown (fib4 kd) tree chloropl ...201020813909
extracellular atp signaling in plants.extracellular adenosine-5'-triphosphate (atp) induces a number of cellular responses in plants and animals. some of the molecular components for purinergic signaling in animal cells appear to be lacking in plant cells, although some cellular responses are similar in both systems [e.g. increased levels of cytosolic free calcium, nitric oxide (no), and reactive oxygen species (ros)]. the purpose of this review is to compare and contrast purinergic signaling mechanisms in animal and plant cells. th ...201020817461
development of amplified fragment length polymorphism-derived functional strain-specific markers to assess the persistence of 10 bacterial strains in soil microcosms.to augment the information on commercial microbial products, we investigated the persistence patterns of high-priority bacterial strains from the canadian domestic substance list (dsl). specific dna markers for each of the 10 dsl bacterial strains were developed using the amplified fragment length polymorphism (aflp) technique, and the fates of dsl strains introduced in soil were assessed by real-time quantitative pcr (qpcr). the results indicated that all dna markers had high specificity at the ...201020817796
economical evolution: microbes reduce the synthetic cost of extracellular proteins.protein evolution is not simply a race toward improved function. because organisms compete for limited resources, fitness is also affected by the relative economy of an organism's proteome. indeed, many abundant proteins contain relatively high percentages of amino acids that are metabolically less taxing for the cell to make, thus reducing cellular cost. however, not all abundant proteins are economical, and many economical proteins are not particularly abundant. here we examined protein compos ...201020824102
specific responses of salmonella enterica to tomato varieties and fruit ripeness identified by in vivo expression technology.recent outbreaks of vegetable-associated gastroenteritis suggest that enteric pathogens colonize, multiply and persist in plants for extended periods of time, eventually infecting people. genetic and physiological pathways, by which enterics colonize plants, are still poorly understood.201020824208
auxin carriers localization drives auxin accumulation in plant cells infected by frankia in casuarina glauca actinorhizal nodules.actinorhizal symbioses are mutualistic interactions between plants and the soil bacteria frankia that lead to the formation of nitrogen-fixing root nodules. little is known about the signaling mechanisms controlling the different steps of the establishment of the symbiosis. the plant hormone auxin has been suggested to play a role. here we report that auxin accumulates within frankia-infected cells in actinorhizal nodules of casuarina glauca. using a combination of computational modeling and exp ...201020826704
novel isonitrile hydratase involved in isonitrile metabolism.we previously discovered n-substituted formamide deformylase (nfda) in arthrobacter pascens f164, which degrades n-substituted formamide (fukatsu, h., hashimoto, y., goda, m., higashibata, h., and kobayashi, m. (2004) proc. natl. acad. sci. u.s.a. 101, 13726-13731). in this study, we found an enzyme involved in the first step of isonitrile metabolism, isonitrile hydratase, that hydrates isonitrile to the corresponding n-substituted formamide. first, we investigated the optimum culture conditions ...201020826798
lazarus1, a duf300 protein, contributes to programmed cell death associated with arabidopsis acd11 and the hypersensitive response.programmed cell death (pcd) is a necessary part of the life of multi-cellular organisms. a type of plant pcd is the defensive hypersensitive response (hr) elicited via recognition of a pathogen by host resistance (r) proteins. the lethal, recessive accelerated cell death 11 (acd11) mutant exhibits hr-like accelerated cell death, and cell death execution in acd11 shares genetic requirements for hr execution triggered by one subclass of r proteins.201020830211
role of the pepper cytochrome p450 gene cacyp450a in defense responses against microbial pathogens.plant cytochrome p450 enzymes are involved in a wide range of biosynthetic reactions, leading to various fatty acid conjugates, plant hormones, or defensive compounds. herein, we have identified the pepper cytochrome p450 gene cacyp450a, which is differentially induced during xanthomonas campestris pv. vesicatoria (xcv) infection. cacyp450a contains a heme-binding motif, pxfxxgxrxcxg, located in the c-terminal region and a hydrophobic membrane anchor region at the n terminal. knock-down of cacyp ...201020830594
pseudomonas syringae virulence factor syringolin a counteracts stomatal immunity by proteasome inhibition.the peptide derivative syringolin a, a product of a mixed nonribosomal peptide and polyketide synthetase, is secreted by certain strains of the phytopathogenic bacterium pseudomonas syringae pv. syringae. syringolin a was shown to be a virulence factor for p. syringae pv. syringae b728a because disease symptoms on its host phaseolus vulgaris (bean) were greatly reduced upon inoculation with syringolin a-negative mutants. syringolin a's mode of action was recently shown to be irreversible proteas ...201020831408
post-translational derepression of invertase activity in source leaves via down-regulation of invertase inhibitor expression is part of the plant defense response.there is increasing evidence that pathogens do not only elicit direct defense responses, but also cause pronounced changes in primary carbohydrate metabolism. cell-wall-bound invertases belong to the key regulators of carbohydrate partitioning and source-sink relations. whereas studies have focused so far only on the transcriptional induction of invertase genes in response to pathogen infection, the role of post-translational regulation of invertase activity has been neglected and was the focus ...201020833735
plant physiology. on the inside. 201020836252
ocp3 is an important modulator of npr1-mediated jasmonic acid-dependent induced defenses in arabidopsis.upon appropriate stimulation, plants increase their level of resistance against future pathogen attack. this phenomenon, known as induced resistance, presents an adaptive advantage due to its reduced fitness costs and its systemic and broad-spectrum nature. in arabidopsis, different types of induced resistance have been defined based on the signaling pathways involved, particularly those dependent on salicylic acid (sa) and/or jasmonic acid (ja).201020836879
disruption of the vacuolar calcium-atpases in arabidopsis results in the activation of a salicylic acid-dependent programmed cell death pathway.calcium (ca(2+)) signals regulate many aspects of plant development, including a programmed cell death pathway that protects plants from pathogens (hypersensitive response). cytosolic ca(2+) signals result from a combined action of ca(2+) influx through channels and ca(2+) efflux through pumps and cotransporters. plants utilize calmodulin-activated ca(2+) pumps (autoinhibited ca(2+)-atpase [aca]) at the plasma membrane, endoplasmic reticulum, and vacuole. here, we show that a double knockout mut ...201020837703
metal hyperaccumulation armors plants against disease.metal hyperaccumulation, in which plants store exceptional concentrations of metals in their shoots, is an unusual trait whose evolutionary and ecological significance has prompted extensive debate. hyperaccumulator plants are usually found on metalliferous soils, and it has been proposed that hyperaccumulation provides a defense against herbivores and pathogens, an idea termed the 'elemental defense' hypothesis. we have investigated this hypothesis using the crucifer thlaspi caerulescens, a hyp ...201020838462
salicylate-mediated suppression of jasmonate-responsive gene expression in arabidopsis is targeted downstream of the jasmonate biosynthesis pathway.jasmonates (jas) and salicylic acid (sa) are plant hormones that play pivotal roles in the regulation of induced defenses against microbial pathogens and insect herbivores. their signaling pathways cross-communicate providing the plant with a regulatory potential to finely tune its defense response to the attacker(s) encountered. in arabidopsis thaliana, sa strongly antagonizes the jasmonic acid (ja) signaling pathway, resulting in the downregulation of a large set of ja-responsive genes, includ ...201020839007
arabidopsis snc2-1d activates receptor-like protein-mediated immunity transduced through wrky70.plant immune receptors belonging to the receptor-like protein (rlp) family contain extracellular leucine-rich repeats (lrrs) and a short cytoplasmic tail linked by a single transmembrane motif. here, we report the identification of snc2-1d (for suppressor of npr1-1, constitutive 2), a semidominant arabidopsis thaliana mutant with constitutively activated defense responses. map-based cloning of snc2-1d showed that it encodes an rlp. the point mutation in snc2-1d leads to substitution of the secon ...201020841424
high-throughput confocal imaging of intact live tissue enables quantification of membrane trafficking in arabidopsis.membrane compartmentalization and trafficking within and between cells is considered an essential cellular property of higher eukaryotes. we established a high-throughput imaging method suitable for the quantitative detection of membrane compartments at subcellular resolution in intact epidermal tissue. whole arabidopsis (arabidopsis thaliana) cotyledon leaves were subjected to quantitative confocal laser microscopy using automated image acquisition, computational pattern recognition, and quanti ...201020841454
pamp (pathogen-associated molecular pattern)-induced changes in plasma membrane compartmentalization reveal novel components of plant immunity.plasma membrane compartmentalization spatiotemporally regulates cell-autonomous immune signaling in animal cells. to elucidate immediate early protein dynamics at the plant plasma membrane in response to the bacterial pathogen-associated molecular pattern (pamp) flagellin (flg22) we employed quantitative mass spectrometric analysis on detergent-resistant membranes (drms) of arabidopsis thaliana suspension cells. this approach revealed rapid and profound changes in drm protein composition followi ...201020843791
structural and kinetic characterization of 4-hydroxy-4-methyl-2-oxoglutarate/4-carboxy-4-hydroxy-2-oxoadipate aldolase, a protocatechuate degradation enzyme evolutionarily convergent with the hpai and dmpg pyruvate aldolases.4-hydroxy-4-methyl-2-oxoglutarate/4-carboxy-4-hydroxy-2-oxoadipate (hmg/cha) aldolase from pseudomonas putida f1 catalyzes the last step of the bacterial protocatechuate 4,5-cleavage pathway. the preferred substrates of the enzyme are 2-keto-4-hydroxy acids with a 4-carboxylate substitution. the enzyme also exhibits oxaloacetate decarboxylation and pyruvate α-proton exchange activity. sodium oxalate is a competitive inhibitor of the aldolase reaction. the ph dependence of k(cat)/k(m) and k(cat) ...201020843800
sgt1 contributes to coronatine signaling and pseudomonas syringae pv. tomato disease symptom development in tomato and arabidopsis.• pseudomonas syringae pv. tomato dc3000 (pst dc3000) causes an economically important bacterial speck disease on tomato and produces symptoms with necrotic lesions surrounded by chlorosis. the chlorosis is mainly attributed to a jasmonic acid (ja)-isoleucine analogue, coronatine (cor), produced by pst dc3000. however, the molecular processes underlying lesion development and cor-induced chlorosis are poorly understood. • in this study, we took advantage of a chlorotic phenotype elicited by cor ...201120854394
identification of cis- and trans-acting elements in phw126, a representative of a novel group of rolling circle plasmids.phw126, pigrk, pigms31 and prao1 are the only known members of a novel and as yet uncharacterised family of rolling circle plasmids. phw126 contains only two open reading frames, of which one shows homology to pmv158-family mobilisation proteins. here we provide evidence that the second open reading frame encodes a replication protein (rep). mutation or deletion of this gene resulted in replication deficient constructs, but providing functional rep from a compatible vector rescued these construc ...201120854841
in search of decoy/guardee to r genes: deciphering the role of sugars in defense against fusarium wilt in chickpea.plant responses are coordinately controlled by both external and internal signals. apt perception of pathogen attack and its appropriate conversion to internal signals ultimately determine the outcome of innate immunity. the present review predicts the involvement of unconventional 'guard/decoy model' in chickpea-fusarium encounter. rapid alkalinization factor is predicted to act as initial 'gatekeeper decoy' counteracting fungal entry. phospholipases and cystatins probably function as 'guardees ...201020855953
lethality and developmental delay in drosophila melanogaster larvae after ingestion of selected pseudomonas fluorescens strains.the fruit fly, drosophila melanogaster, is a well-established model organism for probing the molecular and cellular basis of physiological and immune system responses of adults or late stage larvae to bacterial challenge. however, very little is known about the consequences of bacterial infections that occur in earlier stages of development. we have infected mid-second instar larvae with strains of pseudomonas fluorescens to determine how infection alters the ability of larvae to survive and com ...201020856932
sa-aba antagonism in defense responses.until recently, phytohormones were mostly studied separately. however, recent studies have suggested that the signaling pathways involved are highly interconnected. we recently reported the antagonistic effects of salicylic acid (sa) and abscisic acid (aba) in the lesion mimic mutants, cpr22 and ssi4. after shifting these mutants from high humidity, where the lesion mimic phenotype is suppressed to permissive low humidity condition, both sa and aba pathways were up-regulated. however, the increa ...201020861686
the interplay of lipid acyl hydrolases in inducible plant defense.lipid acyl hydrolases (lah) have received recently increased attention in the context of plant defense. multiple structurally unrelated gene families have been annotated in arabidopsis as encoding potential lipid deacylating enzymes with numerous members being transcriptionally activated upon biotic stress. confirming in silico predictions, experimental data have illustrated the wide subcellular distribution of lahs indicating they likely interact with distinct membrane systems to initiate speci ...201020861688
srfr1 negatively regulates plant nb-lrr resistance protein accumulation to prevent autoimmunity.plant defense responses need to be tightly regulated to prevent auto-immunity, which is detrimental to growth and development. to identify negative regulators of resistance (r) protein-mediated resistance, we screened for mutants with constitutive defense responses in the npr1-1 background. map-based cloning revealed that one of the mutant genes encodes a conserved tpr domain-containing protein previously known as srfr1 (suppressor of rps4-rld). the constitutive defense responses in the srfr1 mu ...201020862316
a high-throughput method for isolation of salicylic acid metabolic mutants.abstract:201020863393
solid sequencing of four vibrio vulnificus genomes enables comparative genomic analysis and identification of candidate clade-specific virulence genes.vibrio vulnificus is the leading cause of reported death from consumption of seafood in the united states. despite several decades of research on molecular pathogenesis, much remains to be learned about the mechanisms of virulence of this opportunistic bacterial pathogen. the two complete and annotated genomic dna sequences of v. vulnificus belong to strains of clade 2, which is the predominant clade among clinical strains. clade 2 strains generally possess higher virulence potential in animal m ...201020863407
structural basis for recognition of s-adenosylhomocysteine by riboswitches.s-adenosyl-(l)-homocysteine (sah) riboswitches are regulatory elements found in bacterial mrnas that up-regulate genes involved in the s-adenosyl-(l)-methionine (sam) regeneration cycle. to understand the structural basis of sah-dependent regulation by rna, we have solved the structure of its metabolite-binding domain in complex with sah. this structure reveals an unusual pseudoknot topology that creates a shallow groove on the surface of the rna that binds sah primarily through interactions wit ...201020864509
characterization of a new bacteriocin, carocin d, from pectobacterium carotovorum subsp. carotovorum pcc21.two different bacteriocins, carotovoricin and carocin s1, had been found in pectobacterium carotovorum subsp. carotovorum, which causes soft-rot disease in diverse plants. previously, we reported that the particular strain pcc21, producing only one high-molecular-weight bacteriocin, carried a new antibacterial activity against the indicator strain pcc3. here, we report that this new antibacterial activity is due to a new bacteriocin produced by strain pcc21 and named carocin d. carocin d is enco ...201020870796
autophosphorylation of tyr-610 in the receptor kinase bak1 plays a role in brassinosteroid signaling and basal defense gene expression.bak1 is a leucine-rich repeat receptor-like kinase that functions as a coreceptor with the brassinosteroid (br) receptor bri1 and the flagellin receptor fls2, and as a negative regulator of programmed cell death. bak1 has been shown to autophosphorylate on numerous serine/threonine sites in vitro as well as to transphosphorylate associated receptor kinases both in vitro and in planta. in the present study we identify tyr-610 in the carboxyl-terminal domain of bak1 as a major site of autophosphor ...201020876109
an ancient p-loop gtpase in rice is regulated by a higher plant-specific regulatory protein.ychf is a subfamily of the obg family in the trafac class of p-loop gtpases. the wide distribution of ychf homologues in both eukarya and bacteria suggests that they are descendents of an ancient protein, yet their physiological roles remain unclear. using the osychf1-osgap1 pair from rice as the prototype, we provide evidence for the regulation of gtpase/atpase activities and rna binding capacity of a plant ychf (osychf1) by its regulatory protein (osgap1). the effects of osgap1 on the subcellu ...201020876569
interaction of 8-hydroxyquinoline with soil environment mediates its ecological function.allelopathic functions of plant-released chemicals are often studied through growth bioassays assuming that these chemicals will directly impact plant growth. this overlooks the role of soil factors in mediating allelopathic activities of chemicals, particularly non-volatiles. here we examined the allelopathic potential of 8-hydroxyquinoline (hq), a chemical reported to be exuded from the roots of centaurea diffusa.201020877629
a multi-pronged search for a common structural motif in the secretion signal of salmonella enterica serovar typhimurium type iii effector proteins.many pathogenic gram-negative bacteria use a type iii secretion system (t3ss) to deliver effector proteins into the host cell where they reprogram host defenses and facilitate pathogenesis. the first 20-30 n-terminal residues usually contain the 'secretion signal' that targets effector proteins for translocation, however, a consensus sequence motif has never been discerned. recent machine-learning approaches, such as support vector machine (svm)-based identification and evaluation of virulence e ...201020877914
comparative analysis of defence responses induced by the endophytic plant growth-promoting rhizobacterium burkholderia phytofirmans strain psjn and the non-host bacterium pseudomonas syringae pv. pisi in grapevine cell suspensions.plant growth-promoting rhizobacteria (pgpr) are beneficial microorganisms that colonize the rhizosphere of many plant species and confer beneficial effects, such as an increase in plant growth. pgpr are also well known as inducers of systemic resistance to pathogens in plants. however, the molecular mechanisms involved locally after direct perception of these bacteria by plant cells still remain largely unknown. burkholderia phytofirmans strain psjn is an endophytic pgpr that colonizes grapevine ...201020881012
studying bacterial transcriptomes using rna-seq.genome-wide studies of bacterial gene expression are shifting from microarray technology to second generation sequencing platforms. rna-seq has a number of advantages over hybridization-based techniques, such as annotation-independent detection of transcription, improved sensitivity and increased dynamic range. early studies have uncovered a wealth of novel coding sequences and non-coding rna, and are revealing a transcriptional landscape that increasingly mirrors that of eukaryotes. already bas ...201020888288
a biosynthetic route to photoclick chemistry on proteins.light-induced chemical reactions exist in nature, regulating many important cellular and organismal functions, e.g., photosensing in prokaryotes and vision formation in mammals. here, we report the genetic incorporation of a photoreactive unnatural amino acid, p-(2-tetrazole)phenylalanine (p-tpa), into myoglobin site-specifically in e. coli by evolving an orthogonal trna/aminoacyl-trna synthetase pair and the use of p-tpa as a bioorthogonal chemical "handle" for fluorescent labeling of p-tpa-enc ...201020919707
the arabidopsis botrytis susceptible1 interactor defines a subclass of ring e3 ligases that regulate pathogen and stress responses.we studied the function of arabidopsis (arabidopsis thaliana) botrytis susceptible1 interactor (boi) in plant responses to pathogen infection and abiotic stress. boi physically interacts with and ubiquitinates arabidopsis bos1, an r2r3myb transcription factor previously implicated in stress and pathogen responses. in transgenic plants expressing the bos1-β-glucuronidase transgene, β-glucuronidase activity could be detected only after inhibition of the proteosome, suggesting that bos1 is a target ...201020921156
genome-enabled research on the ecology of plant-insect interactions. 201020921167
plant immunity: it's the hormones talking, but what do they say? 201020921180
pathogen-associated molecular pattern-triggered immunity: veni, vidi...? 201020921183
control of salicylic acid synthesis and systemic acquired resistance by two members of a plant-specific family of transcription factors.salicylic acid (sa) is a defense hormone required for both local and systemic acquired resistance (sar) in plants. pathogen infections induce sa synthesis through up-regulating the expression of isochorismate synthase 1 (ics1), which encodes a key enzyme in sa production. here we report that both sar deficient 1 (sard1) and cbp60g are key regulators for ics1 induction and sa synthesis. whereas knocking out sard1 compromises basal resistance and sar, overexpression of sard1 constitutively activat ...201020921422
bak1 is not a target of the pseudomonas syringae effector avrpto.plant cell surface-localized receptor kinases such as fls2, efr, and cerk1 play a crucial role in detecting invading pathogenic bacteria. upon stimulation by bacterium-derived ligands, fls2 and efr interact with bak1, a receptor-like kinase, to activate immune responses. a number of pseudomonas syringae effector proteins are known to block immune responses mediated by these receptors. previous reports suggested that both fls2 and bak1 could be targeted by the p. syringae effector avrpto to inhib ...201120923364
proteobactin and a yersiniabactin-related siderophore mediate iron acquisition in proteus mirabilis.proteus mirabilis causes complicated urinary tract infections (utis). while the urinary tract is an iron-limiting environment, iron acquisition remains poorly characterized for this uropathogen. microarray analysis of p. mirabilis hi4320 cultured under iron limitation identified 45 significantly upregulated genes (p ≤ 0.05) that represent 21 putative iron-regulated systems. two gene clusters, pmi0229-0239 and pmi2596-2605, encode putative siderophore systems. pmi0229-0239 encodes a non-ribosomal ...201020923418
bacterial nanomachines: the flagellum and type iii injectisome.the bacterial flagellum and the virulence-associated injectisome are complex, structurally related nanomachines that bacteria use for locomotion or the translocation of virulence factors into eukaryotic host cells. the assembly of both structures and the transfer of extracellular proteins is mediated by a unique, multicomponent transport apparatus, the type iii secretion system. here, we discuss the significant progress that has been made in recent years in the visualization and functional chara ...201020926516
jasmonate perception by inositol-phosphate-potentiated coi1-jaz co-receptor.jasmonates are a family of plant hormones that regulate plant growth, development and responses to stress. the f-box protein coronatine insensitive 1 (coi1) mediates jasmonate signalling by promoting hormone-dependent ubiquitylation and degradation of transcriptional repressor jaz proteins. despite its importance, the mechanism of jasmonate perception remains unclear. here we present structural and pharmacological data to show that the true arabidopsis jasmonate receptor is a complex of both coi ...201020927106
functional characterization of replication and stability factors of an incompatibility group p-1 plasmid from xylella fastidiosa.xylella fastidiosa strain riv11 harbors a 25-kbp plasmid (pxf-riv11) belonging to the incp-1 incompatibility group. replication and stability factors of pxf-riv11 were identified and used to construct plasmids able to replicate in x. fastidiosa and escherichia coli. replication in x. fastidiosa required a 1.4-kbp region from pxf-riv11 containing a replication initiation gene (trfa) and the adjacent origin of dna replication (oriv). constructs containing trfa and oriv from pveis01, a related incp ...201020935126
photoreceptors crytochrome2 and phytochrome b control chromatin compaction in arabidopsis.development and acclimation processes to the environment are associated with large-scale changes in chromatin compaction in arabidopsis (arabidopsis thaliana). here, we studied the effects of light signals on chromatin organization. a decrease in light intensity induces a large-scale reduction in chromatin compaction. this low light response is reversible and shows strong natural genetic variation. moreover, the degree of chromatin compaction is affected by light quality signals relevant for nat ...201020935177
arachidonic acid: an evolutionarily conserved signaling molecule modulates plant stress signaling networks.fatty acid structure affects cellular activities through changes in membrane lipid composition and the generation of a diversity of bioactive derivatives. eicosapolyenoic acids are released into plants upon infection by oomycete pathogens, suggesting they may elicit plant defenses. we exploited transgenic arabidopsis thaliana plants (designated ep) producing eicosadienoic, eicosatrienoic, and arachidonic acid (aa), aimed at mimicking pathogen release of these compounds. we also examined their ef ...201020935246
an effector-targeted protease contributes to defense against phytophthora infestans and is under diversifying selection in natural hosts.since the leaf apoplast is a primary habitat for many plant pathogens, apoplastic proteins are potent, ancient targets for apoplastic effectors secreted by plant pathogens. so far, however, only a few apoplastic effector targets have been identified and characterized. here, we discovered that the papain-like cysteine protease c14 is a new common target of epic1 and epic2b, two apoplastic, cystatin-like proteins secreted by the potato (solanum tuberosum) late blight pathogen phytophthora infestan ...201020940351
analysis and comparison of the pan-genomic properties of sixteen well-characterized bacterial genera.the increasing availability of whole genome sequences allows the gene or protein content of different organisms to be compared, leading to burgeoning interest in the relatively new subfield of pan-genomics. however, while several studies have analyzed protein content relationships in specific groups of bacteria, there has yet to be a study that provides a general characterization of protein content relationships in a broad range of bacteria.201020942950
two putative rna-binding proteins function with unequal genetic redundancy in the mos4-associated complex.the mos4-associated complex (mac) is a highly conserved nuclear protein complex associated with the spliceosome. we recently purified the mac from arabidopsis (arabidopsis thaliana) nuclei, identified its potential components by mass spectrometry, and showed that at least five core proteins in the mac are required for defense responses in plants. here, we report the characterization of a putative rna-binding protein identified in the mac named mac5a and its close homolog mac5b. we confirmed that ...201020943852
global transcript profiling of transgenic plants constitutively overexpressing the rna-binding protein atgrp7.the clock-controlled rna-binding protein atgrp7 influences circadian oscillations of its own transcript at the post-transcriptional level. to identify additional targets that are regulated by atgrp7, transcript profiles of transgenic plants constitutively overexpressing atgrp7 (atgrp7-ox) and wild type plants were compared.201020946635
the role of malate in plant homeostasis.malate is a central metabolite of the plant cell with important roles in plant physiology and metabolism. here, we summarize the most recent advances in our understanding of malate homeostasis in central metabolism, guard cell functioning, and root exudation.200920948638
do apicomplexan parasites hijack the host cell microrna pathway for their intracellular development?rna silencing plays an important role in development through the action of micrornas, which fine tune the expression of a large portion of the genome. it is also very important in innate immune responses, especially in antiviral and antibacterial defenses in plants, insects, and animals. two recent papers now indicate that apicomplexan parasites display the ability to interfere with host microrna populations.201020948791
autoimmunity in arabidopsis acd11 is mediated by epigenetic regulation of an immune receptor.certain pathogens deliver effectors into plant cells to modify host protein targets and thereby suppress immunity. these target modifications can be detected by intracellular immune receptors, or resistance (r) proteins, that trigger strong immune responses including localized host cell death. the accelerated cell death 11 (acd11) "lesion mimic" mutant of arabidopsis thaliana exhibits autoimmune phenotypes such as constitutive defense responses and cell death without pathogen perception. acd11 e ...201020949080
units of plasticity in bacterial genomes: new insight from the comparative genomics of two bacteria interacting with invertebrates, photorhabdus and xenorhabdus.flexible genomes facilitate bacterial evolution and are classically organized into polymorphic strain-specific segments called regions of genomic plasticity (rgps). using a new web tool, rgpfinder, we investigated plasticity units in bacterial genomes, by exhaustive description of the rgps in two photorhabdus and two xenorhabdus strains, belonging to the enterobacteriaceae and interacting with invertebrates (insects and nematodes).201020950463
screening for resistance against pseudomonas syringae in rice-fox arabidopsis lines identified a putative receptor-like cytoplasmic kinase gene that confers resistance to major bacterial and fungal pathogens in arabidopsis and rice.approximately 20,000 of the rice-fox arabidopsis transgenic lines, which overexpress 13,000 rice full-length cdnas at random in arabidopsis, were screened for bacterial disease resistance by dip inoculation with pseudomonas syringae pv. tomato dc3000 (pst dc3000). the identities of the overexpressed genes were determined in 72 lines that showed consistent resistance after three independent screens. pst dc3000 resistance was verified for 19 genes by characterizing other independent arabidopsis li ...201020955180
what is type vi secretion doing in all those bugs?the identification of bacterial secretion systems capable of translocating substrates into eukaryotic cells via needle-like appendages has opened fruitful and exciting areas of microbial pathogenesis research. the recent discovery of the type vi secretion system (t6ss) was met with early speculation that it too acts as a 'needle' that pathogens aim at host cells. new reports demonstrate that certain t6sss are potent mediators of interbacterial interactions. in light of these findings, we examine ...201020961764
pr-1 gene family of grapevine: a uniquely duplicated pr-1 gene from a vitis interspecific hybrid confers high level resistance to bacterial disease in transgenic tobacco.a functional contribution of pathogenesis-related 1 (pr-1) proteins to host defense has been established. however, systematic investigation of the pr-1 gene family in grapevine (vitis spp.) has not been conducted previously. through mining genomic databases, we identified 21 pr-1 genes from the vitis vinifera genome. polypeptides encoded by putative pr-1 genes had a signal sequence of about 25 residues and a mature protein of 10.9-29 kda in size. pr-1 mature proteins contained a highly conserved ...201020967449
a computational-based update on micrornas and their targets in barley (hordeum vulgare l.).many plant species have been investigated in the last years for the identification and characterization of the corresponding mirnas, nevertheless extensive studies are not yet available on barley (at the time of this writing). to extend and to update information on mirnas and their targets in barley and to identify candidate polymorphisms at mirna target sites, the features of previously known plant mirnas have been used to systematically search for barley mirna homologues and targets in the pub ...201020969764
structural and functional analysis of the type iii secretion system from pseudomonas fluorescens q8r1-96.pseudomonas fluorescens q8r1-96 represents a group of rhizosphere strains responsible for the suppressiveness of agricultural soils to take-all disease of wheat. it produces the antibiotic 2,4-diacetylphloroglucinol and aggressively colonizes the roots of cereal crops. in this study, we analyzed the genome of q8r1-96 and identified a type iii protein secretion system (t3ss) gene cluster that has overall organization similar to that of the t3ss gene cluster of the plant pathogen pseudomonas syrin ...201020971913
structural and functional analysis of the type iii secretion system from pseudomonas fluorescens q8r1-96.pseudomonas fluorescens q8r1-96 represents a group of rhizosphere strains responsible for the suppressiveness of agricultural soils to take-all disease of wheat. it produces the antibiotic 2,4-diacetylphloroglucinol and aggressively colonizes the roots of cereal crops. in this study, we analyzed the genome of q8r1-96 and identified a type iii protein secretion system (t3ss) gene cluster that has overall organization similar to that of the t3ss gene cluster of the plant pathogen pseudomonas syrin ...201020971913
assessing stomatal response to live bacterial cells using whole leaf imaging.stomata are natural openings in the plant epidermis responsible for gas exchange between plant interior and environment. they are formed by a pair of guard cells, which are able to close the stomatal pore in response to a number of external factors including light intensity, carbon dioxide concentration, and relative humidity (rh). the stomatal pore is also the main route for pathogen entry into leaves, a crucial step for disease development. recent studies have unveiled that closure of the pore ...201020972403
the tomato xylem sap protein xsp10 is required for full susceptibility to fusarium wilt disease.xsp10 is an abundant 10 kda protein found in the xylem sap of tomato. the protein displays structural similarity to plant lipid transfer proteins (ltps). ltps are involved in various physiological processes, including disease resistance, and some are able to bind and transfer diverse lipid molecules. xsp10 abundance in xylem sap declines upon infection with fusarium oxysporum f. sp. lycopersici (fol), implying involvement of xsp10 in the plant-pathogen interaction. here, the biochemical characte ...201020974736
the tomato xylem sap protein xsp10 is required for full susceptibility to fusarium wilt disease.xsp10 is an abundant 10 kda protein found in the xylem sap of tomato. the protein displays structural similarity to plant lipid transfer proteins (ltps). ltps are involved in various physiological processes, including disease resistance, and some are able to bind and transfer diverse lipid molecules. xsp10 abundance in xylem sap declines upon infection with fusarium oxysporum f. sp. lycopersici (fol), implying involvement of xsp10 in the plant-pathogen interaction. here, the biochemical characte ...201020974736
computational prediction of type iii and iv secreted effectors in gram-negative bacteria.in this review, we provide an overview of the methods employed in four recent studies that described novel methods for computational prediction of secreted effectors from type iii and iv secretion systems in gram-negative bacteria. we present the results of these studies in terms of performance at accurately predicting secreted effectors and similarities found between secretion signals that may reflect biologically relevant features for recognition. we discuss the web-based tools for secreted ef ...201020974833
computational prediction of type iii and iv secreted effectors in gram-negative bacteria.in this review, we provide an overview of the methods employed in four recent studies that described novel methods for computational prediction of secreted effectors from type iii and iv secretion systems in gram-negative bacteria. we present the results of these studies in terms of performance at accurately predicting secreted effectors and similarities found between secretion signals that may reflect biologically relevant features for recognition. we discuss the web-based tools for secreted ef ...201020974833
discovery of novel secreted virulence factors from salmonella enterica serovar typhimurium by proteomic analysis of culture supernatants.salmonella enterica serovar typhimurium is a leading cause of acute gastroenteritis throughout the world. this pathogen has two type iii secretion systems (ttss) encoded in salmonella pathogenicity islands 1 and 2 (spi-1 and spi-2) that deliver virulence factors (effectors) to the host cell cytoplasm and are required for virulence. while many effectors have been identified and at least partially characterized, the full repertoire of effectors has not been catalogued. in this proteomic study, we ...201020974834
discovery of novel secreted virulence factors from salmonella enterica serovar typhimurium by proteomic analysis of culture supernatants.salmonella enterica serovar typhimurium is a leading cause of acute gastroenteritis throughout the world. this pathogen has two type iii secretion systems (ttss) encoded in salmonella pathogenicity islands 1 and 2 (spi-1 and spi-2) that deliver virulence factors (effectors) to the host cell cytoplasm and are required for virulence. while many effectors have been identified and at least partially characterized, the full repertoire of effectors has not been catalogued. in this proteomic study, we ...201020974834
genome-wide identification of hrpl-regulated genes in the necrotrophic phytopathogen dickeya dadantii 3937.background: dickeya dadantii is a necrotrophic pathogen causing disease in many plants. previous studies have demonstrated that the type iii secretion system (t3ss) of d. dadantii is required for full virulence. hrpl is an alternative sigma factor that binds to the hrp box promoter sequence of t3ss genes to up-regulate their expression. methodology/principal findings: to explore the inventory of hrpl-regulated genes of d. dadantii 3937 (3937), transcriptome profiles of wild-type 3937 and a hrpl ...201020976052
4-formylaminooxyvinylglycine, an herbicidal germination-arrest factor from pseudomonas rhizosphere bacteria.a new oxyvinylglycine has been identified as a naturally occurring herbicide that irreversibly arrests germination of the seeds of grassy weeds, such as annual bluegrass (poa annua), without significantly affecting the growth of established grass seedlings and mature plants or germination of the seeds of broadleaf plant species (dicots). previously, pseudomonas fluorescens wh6 and over 20 other rhizosphere bacteria were isolated and selected for their ability to arrest germination of p. annua se ...201020979386
biochemical and structural studies of a hect-like ubiquitin ligase from escherichia coli o157:h7.many microbial pathogens deliver effector proteins via the type iii secretion system into infected host cells. elucidating the function of these effectors is essential for our understanding of pathogenesis. here, we describe biochemical and structural characterization of an effector protein (nlel) from escherichia coli o157:h7, a widespread pathogen causing severe foodborne diseases. we show that nlel functionally and structurally mimics eukaryotic hect e3 ligases and catalyzes formation of unan ...201020980253
biochemical and structural studies of a hect-like ubiquitin ligase from escherichia coli o157:h7.many microbial pathogens deliver effector proteins via the type iii secretion system into infected host cells. elucidating the function of these effectors is essential for our understanding of pathogenesis. here, we describe biochemical and structural characterization of an effector protein (nlel) from escherichia coli o157:h7, a widespread pathogen causing severe foodborne diseases. we show that nlel functionally and structurally mimics eukaryotic hect e3 ligases and catalyzes formation of unan ...201020980253
homologue structure of the slac1 anion channel for closing stomata in leaves.the plant slac1 anion channel controls turgor pressure in the aperture-defining guard cells of plant stomata, thereby regulating the exchange of water vapour and photosynthetic gases in response to environmental signals such as drought or high levels of carbon dioxide. here we determine the crystal structure of a bacterial homologue (haemophilus influenzae) of slac1 at 1.20 å resolution, and use structure-inspired mutagenesis to analyse the conductance properties of slac1 channels. slac1 is a sy ...201020981093
lipopolysaccharide mobility in leaf tissue of arabidopsis thaliana.bacterial lipopolysaccharides (lps) are triggers of defence responses in plants, and induce local as well as systemic acquired resistance. arabidopsis thaliana plants pretreated with lps show an increased resistance to the virulent bacterial plant pathogen pseudomonas syringae pv. tomato dc3000. to investigate the mobilization and transport of lps in arabidopsis leaves, fluorescently labelled lps (alexa fluor® 488 conjugate) from salmonella minnesota was used. leaves were pressure infiltrated wi ...201021029320
effector-triggered innate immunity contributes arabidopsis resistance to xanthomonas campestris.xanthomonas campestris pv. campestris, the causal agent of black rot disease, depends on its type iii secretion system (ttss) to infect cruciferous plants, including brassica oleracea, b. napus and arabidopsis. previous studies on the arabidopsis-pseudomonas syringae model pathosystem have indicated that a major function of ttss from virulent bacteria is to suppress host defences triggered by pathogen-associated molecular patterns. similar analyses have not been made for the arabidopsis-x. campe ...201021029323
hahb10, a sunflower hd-zip ii transcription factor, participates in the induction of flowering and in the control of phytohormone-mediated responses to biotic stress.the transcription factor hahb10 belongs to the sunflower (helianthus annuus) hd-zip ii subfamily and it has been previously associated with the induction of flowering. in this study it is shown that hahb10 is expressed in sunflower leaves throughout the vegetative stage and in stamens during the reproductive stage. in short-day inductive conditions the expression of this gene is induced in shoot apexes together with the expression of the flowering genes haft and haap1. transgenic arabidopsis pla ...201021030388
low oleic acid-derived repression of jasmonic acid-inducible defense responses requires the wrky50 and wrky51 proteins.signaling induced upon a reduction in oleic acid (18:1) levels simultaneously up-regulates salicylic acid (sa)-mediated responses and inhibits jasmonic acid (ja)-inducible defenses, resulting in enhanced resistance to biotrophs but increased susceptibility to necrotrophs. sa and the signaling component enhanced disease susceptibility1 function redundantly in this low-18:1-derived pathway to induce sa signaling but do not function in the repression of ja responses. we show that repression of ja-m ...201021030507
low oleic acid-derived repression of jasmonic acid-inducible defense responses requires the wrky50 and wrky51 proteins.signaling induced upon a reduction in oleic acid (18:1) levels simultaneously up-regulates salicylic acid (sa)-mediated responses and inhibits jasmonic acid (ja)-inducible defenses, resulting in enhanced resistance to biotrophs but increased susceptibility to necrotrophs. sa and the signaling component enhanced disease susceptibility1 function redundantly in this low-18:1-derived pathway to induce sa signaling but do not function in the repression of ja responses. we show that repression of ja-m ...201021030507
n-acylation during glidobactin biosynthesis by the tridomain nonribosomal peptide synthetase module glbf.glidobactins are hybrid nrps-pks natural products that function as irreversible proteasome inhibitors. a variety of medium chain 2(e),4(e)-diene fatty acids n-acylate the peptidolactam core and contribute significantly to the potency of proteasome inhibition. we have expressed the initiation nrps module glbf (c-a-t) in escherichia coli and observe soluble active protein only on coexpression with the 8 kda mbth-like protein, glbe. following adenylation and installation of thr as a t-domain thioes ...201021035730
development of an efficient real-time quantitative pcr protocol for detection of xanthomonas arboricola pv. pruni in prunus species.xanthomonas arboricola pv. pruni, the causal agent of bacterial spot disease of stone fruit, is considered a quarantine organism by the european union and the european and mediterranean plant protection organization (eppo). the bacterium can undergo an epiphytic phase and/or be latent and can be transmitted by plant material, but currently, only visual inspections are used to certify plants as being x. arboricola pv. pruni free. a novel and highly sensitive real-time taqman pcr detection protoco ...201021037298
development of an efficient real-time quantitative pcr protocol for detection of xanthomonas arboricola pv. pruni in prunus species.xanthomonas arboricola pv. pruni, the causal agent of bacterial spot disease of stone fruit, is considered a quarantine organism by the european union and the european and mediterranean plant protection organization (eppo). the bacterium can undergo an epiphytic phase and/or be latent and can be transmitted by plant material, but currently, only visual inspections are used to certify plants as being x. arboricola pv. pruni free. a novel and highly sensitive real-time taqman pcr detection protoco ...201021037298
limitation of nocturnal atp import into chloroplasts seems to affect hormonal crosstalk, prime defense, and enhance disease resistance in arabidopsis thaliana.when grown under short-day conditions at low light, leaves of an arabidopsis thaliana (accession col-0) mutant with defects in the two genes encoding plastid atp/adp antiporters (so-called ntt1-2 null mutants) display a variety of physiological changes. these include the formation of necrotic lesions and the accumulation of hydrogen peroxide in the leaves. here, we show that, under short-day conditions, leaves of the ntt1-2 mutant display enhanced resistance to hyaloperonospora arabidopsidis, bo ...201021039274
maladaptation in wild populations of the generalist plant pathogen pseudomonas syringae.multihost pathogens occur widely on both natural and agriculturally managed hosts. despite the importance of such generalists, evolutionary studies of host-pathogen interactions have largely focused on tightly coupled interactions between species pairs. we characterized resistance in a collection of arabidopsis thaliana hosts, including 24 accessions collected from the midwest usa and 24 from around the world, and patterns of virulence in a collection of pseudomonas syringae strains, including 2 ...201021044058
maladaptation in wild populations of the generalist plant pathogen pseudomonas syringae.multihost pathogens occur widely on both natural and agriculturally managed hosts. despite the importance of such generalists, evolutionary studies of host-pathogen interactions have largely focused on tightly coupled interactions between species pairs. we characterized resistance in a collection of arabidopsis thaliana hosts, including 24 accessions collected from the midwest usa and 24 from around the world, and patterns of virulence in a collection of pseudomonas syringae strains, including 2 ...201021044058
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