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space microbiology.the responses of microorganisms (viruses, bacterial cells, bacterial and fungal spores, and lichens) to selected factors of space (microgravity, galactic cosmic radiation, solar uv radiation, and space vacuum) were determined in space and laboratory simulation experiments. in general, microorganisms tend to thrive in the space flight environment in terms of enhanced growth parameters and a demonstrated ability to proliferate in the presence of normally inhibitory levels of antibiotics. the mecha ...201020197502
rapid differentiation of francisella species and subspecies by fluorescent in situ hybridization targeting the 23s rrna.francisella (f.) tularensis is the causative agent of tularemia. due to its low infectious dose, ease of dissemination and high case fatality rate, f. tularensis was the subject in diverse biological weapons programs and is among the top six agents with high potential if misused in bioterrorism. microbiological diagnosis is cumbersome and time-consuming. methods for the direct detection of the pathogen (immunofluorescence, pcr) have been developed but are restricted to reference laboratories.201020205957
measurement of intrinsic rate constants in the tyrosine hydroxylase reaction.tyrosine hydroxylase (tyrh) is a pterin-dependent mononuclear non-heme aromatic amino acid hydroxylase that catalyzes the conversion of tyrosine to dihydroxyphenylalanine (dopa). chemical quench analyses of the enzymatic reaction show a burst of dopa formation, followed by a linear rate equal to the k(cat) value at both 5 and 30 degrees c. the effects of increasing solvent viscosity confirm that k(cat) is approximately 84% limited by diffusion, most probably due to slow product release, and that ...201020025246
complete genome sequence of the fire blight pathogen erwinia pyrifoliae dsm 12163t and comparative genomic insights into plant pathogenicity.erwinia pyrifoliae is a newly described necrotrophic pathogen, which causes fire blight on asian (nashi) pear and is geographically restricted to eastern asia. relatively little is known about its genetics compared to the closely related main fire blight pathogen e. amylovora.201020047678
an automated system for rapid non-destructive enumeration of growing microbes.the power and simplicity of visual colony counting have made it the mainstay of microbiological analysis for more than 130 years. a disadvantage of the method is the long time required to generate visible colonies from cells in a sample. new rapid testing technologies generally have failed to maintain one or more of the major advantages of culture-based methods.201020062794
chromobacterium violaceum infection in a free-ranging howler monkey in costa rica.chromobacterium violaceum is a gram-negative saprobe bacterium that is a rare opportunistic pathogen in mammals. there are numerous reports in humans including fatalities, but no record exists in free-ranging nonhuman primates. here we report an infection by c. violaceum in a wild adult male howler monkey (alouatta palliata) captured at ballena marine national park, in southwestern costa rica. the individual had severe skin lesions over its extremities; gross findings included multiple skin ulce ...201020090050
expression of phosphofructokinase in neisseria meningitidis.neisseria meningitidis serogroup b is a pathogen that can infect diverse sites within the human host. according to the n. meningitidis genomic information and experimental observations, glucose can be completely catabolized through the entner-doudoroff pathway and the pentose phosphate pathway. the embden-meyerhof-parnas pathway is not functional, because the gene for phosphofructokinase (pfk) is not present. the phylogenetic distribution of pfk indicates that in most obligate aerobic organisms, ...201019797358
inhibition of quorum-sensing signals by essential oils.the role of quorum sensing (qs) is well known in microbial pathogenicity and antibiotic resistance. qs is responsible for motility, swarming, and biofilm production based on the signal molecules, e.g., acylated homoserine lactones (ahls) produced by micro-organisms above certain population density. the inhibition of qs may reduce pathogenicity, antibiotic resistance and biofilm formation in systemic and local infections. the homoserine lactones and other transmitters contribute to antibiotic res ...201019827025
sepl resembles an aberrant effector in binding to a class 1 type iii secretion chaperone and carrying an n-terminal secretion signal.here we show that the type iii secretion gatekeeper protein sepl resembles an aberrant effector protein in binding to a class 1 type iii secretion chaperone (orf12, here renamed cesl). we also show that short n-terminal fragments (≤70 amino acids) from sepl are capable of targeting fusion proteins for secretion and translocation.201020833800
regulation of the violacein biosynthetic gene cluster by acylhomoserine lactone-mediated quorum sensing in chromobacterium violaceum atcc 12472.chromobacterium violaceum produces the purple pigment violacein by quorum-sensing regulation. 20-bp of the lux box-like sequence was found upstream of vioa in c. violaceum atcc 12472. cvir received c10-hsl and c6-hsl and activated the transcription of vioa in escherichia coli. however, in strain atcc 12472, c6-hsl inhibited both c10-hsl-mediated violacein production and the transcription of vioa.201020944413
isolation and characterization of new potential probiotic bacteria based on quorum-sensing system.this work was aimed at identifying strains which can degrade quorum-sensing (qs) molecules from fish gut, with properties suitable for use as probiotic in aquaculture.201020955192
nonflowering plants possess a unique folate-dependent phenylalanine hydroxylase that is localized in chloroplasts.tetrahydropterin-dependent aromatic amino acid hydroxylases (aahs) are known from animals and microbes but not plants. a survey of genomes and ests revealed aah-like sequences in gymnosperms, mosses, and algae. analysis of full-length aah cdnas from pinus taeda, physcomitrella patens, and chlamydomonas reinhardtii indicated that the encoded proteins form a distinct clade within the aah family. these proteins were shown to have phe hydroxylase activity by functional complementation of an escheric ...201020959559
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
rationale for possible targeting of histone deacetylase signaling in cancer diseases with a special reference to pancreatic cancer.there is ongoing interest to identify signaling pathways and genes that play a key role in carcinogenesis and the development of resistance to antitumoral drugs. given that histone deacetylases (hdacs) interact with various partners through complex molecular mechanims leading to the control of gene expression, they have captured the attention of a large number of researchers. as a family of transcriptional corepressors, they have emerged as important regulators of cell differentiation, cell cycl ...201020981265
rationale for possible targeting of histone deacetylase signaling in cancer diseases with a special reference to pancreatic cancer.there is ongoing interest to identify signaling pathways and genes that play a key role in carcinogenesis and the development of resistance to antitumoral drugs. given that histone deacetylases (hdacs) interact with various partners through complex molecular mechanims leading to the control of gene expression, they have captured the attention of a large number of researchers. as a family of transcriptional corepressors, they have emerged as important regulators of cell differentiation, cell cycl ...201020981265
the siderophore pyoverdine of pseudomonas syringae pv. tabaci 6605 is an intrinsic virulence factor in host tobacco infection.to investigate the role of iron uptake mediated by the siderophore pyoverdine in the virulence of the plant pathogen pseudomonas syringae pv. tabaci 6605, three predicted pyoverdine synthesis-related genes, pvdj, pvdl, and fpva, were mutated. the pvdj, pvdl, and fpva genes encode the pyoverdine side chain peptide synthetase iii l-thr-l-ser component, the pyoverdine chromophore synthetase, and the tonb-dependent ferripyoverdine receptor, respectively. the delta pvdj and delta pvdl mutants were un ...201019854904
the siderophore pyoverdine of pseudomonas syringae pv. tabaci 6605 is an intrinsic virulence factor in host tobacco infection.to investigate the role of iron uptake mediated by the siderophore pyoverdine in the virulence of the plant pathogen pseudomonas syringae pv. tabaci 6605, three predicted pyoverdine synthesis-related genes, pvdj, pvdl, and fpva, were mutated. the pvdj, pvdl, and fpva genes encode the pyoverdine side chain peptide synthetase iii l-thr-l-ser component, the pyoverdine chromophore synthetase, and the tonb-dependent ferripyoverdine receptor, respectively. the delta pvdj and delta pvdl mutants were un ...201019854904
identification of catechin as one of the flavonoids from combretum albiflorum bark extract that reduces the production of quorum-sensing-controlled virulence factors in pseudomonas aeruginosa pao1.quorum-sensing (qs) regulates the production of key virulence factors in pseudomonas aeruginosa and other important pathogenic bacteria. in this report, extracts of leaves and bark of combretum albiflorum (tul.) jongkind (combretaceae) were found to quench the production of qs-dependent factors in p. aeruginosa pao1. chromatographic fractionation of the crude active extract generated several active fractions containing flavonoids, as shown by their typical spectral features. purification and str ...201019854927
identification of catechin as one of the flavonoids from combretum albiflorum bark extract that reduces the production of quorum-sensing-controlled virulence factors in pseudomonas aeruginosa pao1.quorum-sensing (qs) regulates the production of key virulence factors in pseudomonas aeruginosa and other important pathogenic bacteria. in this report, extracts of leaves and bark of combretum albiflorum (tul.) jongkind (combretaceae) were found to quench the production of qs-dependent factors in p. aeruginosa pao1. chromatographic fractionation of the crude active extract generated several active fractions containing flavonoids, as shown by their typical spectral features. purification and str ...201019854927
production of cell-cell signalling molecules by bacteria isolated from human chronic wounds.to (i) identify chronic wound bacteria and to test their ability to produce acyl-homoserine-lactones (ahls) and autoinducer-2 (ai-2) cell-cell signalling molecules and (ii) determine whether chronic wound debridement samples might contain these molecules.201019840177
production of cell-cell signalling molecules by bacteria isolated from human chronic wounds.to (i) identify chronic wound bacteria and to test their ability to produce acyl-homoserine-lactones (ahls) and autoinducer-2 (ai-2) cell-cell signalling molecules and (ii) determine whether chronic wound debridement samples might contain these molecules.201019840177
immunomodulatory, analgesic and antipyretic effects of violacein isolated from chromobacterium violaceum.violacein was isolated from chromobacterium violaceum, a soil gram negative bacterium collected from the forest water body soil sample of kolli hills; tamil nadu, india. in the present study the immunomodulatory, analgesic and antipyretic activities of violacein were investigated in wistar rats and mice. analgesic effect was evaluated by acetic acid- induced writhing, formalin induced paw licking and hotplate tests. immunomodulatory effect was investigated by using ovalbumin- induced active paw ...201019576742
measurement of the intramolecular isotope effect on aliphatic hydroxylation by chromobacterium violaceum phenylalanine hydroxylase.the non-heme iron enzyme phenylalanine hydroxylase from chromobacterium violaceum has previously been shown to catalyze the hydroxylation of benzylic and aliphatic carbons in addition to the normal aromatic hydroxylation reaction. the intrinsic isotope effect for hydroxylation of 3-cyclochexylalanine by the enzyme was determined in order to gain insight into the reactivity of the iron center. with 3-[(2)h(11)-cyclohexyl]alanine as the substrate, the isotope effect on the k(cat) value was 1, cons ...201020355730
bacillus pumilus of palk bay origin inhibits quorum-sensing-mediated virulence factors in gram-negative bacteria.the aim of the current study was to inhibit quoring-sensing(qs)-mediated virulence factors of representative gram-negative bacteria by marine bacterial isolates. bacteria isolated from palk bay sediments were screened for anti-qs activity. eleven strains inhibited qs signals in chromobacterium violaceum (atcc 12472) and c. violaceum cv026. the marine bacterial strain s8-07 reduced the accumulation of n-acyl homoserine lactone (ahls) and showed significant inhibition of lasa protease(76%), lasb e ...201020381609
novel anti-infective compounds from marine bacteria.as a result of the continuous evolution of microbial pathogens towards antibiotic-resistance, there have been demands for the development of new and effective antimicrobial compounds. since the 1960s, the scientific literature has accumulated many publications about novel pharmaceutical compounds produced by a diverse range of marine bacteria. indeed, marine micro-organisms continue to be a productive and successful focus for natural products research, with many newly isolated compounds possessi ...201020411112
finding new enzymes from bacterial physiology: a successful approach illustrated by the detection of novel oxidases in marinomonas mediterranea.the identification and study of marine microorganisms with unique physiological traits can be a very powerful tool discovering novel enzymes of possible biotechnological interest. this approach can complement the enormous amount of data concerning gene diversity in marine environments offered by metagenomic analysis, and can help to place the activities associated with those sequences in the context of microbial cellular metabolism and physiology. accordingly, the detection and isolation of micr ...201020411113
production of metabolites as bacterial responses to the marine environment.bacteria in marine environments are often under extreme conditions of e.g., pressure, temperature, salinity, and depletion of micronutrients, with survival and proliferation often depending on the ability to produce biologically active compounds. some marine bacteria produce biosurfactants, which help to transport hydrophobic low water soluble substrates by increasing their bioavailability. however, other functions related to heavy metal binding, quorum sensing and biofilm formation have been de ...201020411122
growth inhibition and pro-apoptotic activity of violacein in ehrlich ascites tumor.the continuing threat to biodiversity lends urgency to the need of identification of sustainable source of natural products. this is not so much trouble if there is a microbial source of the compound. herein, violacein, a natural indolic pigment extracted from chromobacterium violaceum, was evaluated for its antitumoral potential against the ehrlich ascites tumor (eat) in vivo and in vitro. evaluation of violacein cytotoxicity using different endpoints indicated that eat cells were twofold (ic(5 ...201020416285
pentaplexed quantitative real-time pcr assay for the simultaneous detection and quantification of botulinum neurotoxin-producing clostridia in food and clinical samples.botulinum neurotoxins are produced by the anaerobic bacterium clostridium botulinum and are divided into seven distinct serotypes (a to g) known to cause botulism in animals and humans. in this study, a multiplexed quantitative real-time pcr assay for the simultaneous detection of the human pathogenic c. botulinum serotypes a, b, e, and f was developed. based on the taqman chemistry, we used five individual primer-probe sets within one pcr, combining both minor groove binder- and locked nucleic ...201020435756
novel tryptophan metabolites, chromoazepinone a, b and c, produced by a blocked mutant of chromobacterium violaceum, the biosynthetic implications and the biological activity of chromoazepinone a and b.chromobacterium violaceum produces tryptophan metabolites, purple pigments of violacein and deoxyviolacein. a blocked mutant was prepared with n-methyl-n'-nitrosoguanidine to gain insights into the biosynthetic mechanisms of the pigments. five tryptophan metabolites were isolated: three novel compounds, named chromoazepinone a, b and c and two known compounds, chromopyrrolic acid and arcyriarubin a. the structure determinations of the three novel compounds are described. the biosynthetic pathway ...201020490411
chromobacterium pathogenicity island 1 type iii secretion system is a major virulence determinant for chromobacterium violaceum-induced cell death in hepatocytes.summary chromobacterium violaceum is a gram-negative bacterium that causes fatal septicaemia in humans and animals. c. violaceum atcc 12472 possesses genes associated with two distinct type iii secretion systems (t3sss). one of these systems is encoded by chromobacterium pathogenicity islands 1 and 1a (cpi-1/-1a), another is encoded by chromobacterium pathogenicity island 2 (cpi-2). here we show that c. violaceum causes fulminant hepatitis in a mouse infection model, and cpi-1/-1a-encoded t3ss i ...201020545857
antimycobacterial activity in vitro of pigments isolated from antarctic bacteria.in this study, we describe the antimycobacterial activity of two pigments, violacein, a purple violet pigment from janthinobacterium sp. ant5-2 (j-pvp), and flexirubin, a yellow-orange pigment from flavobacterium sp. ant342 (f-yop). these pigments were isolated from bacterial strains found in the land-locked freshwater lakes of schirmacher oasis, east antarctica. the minimum inhibitory concentrations (mics) of these pigments for avirulent and virulent mycobacteria were determined by the micropla ...201020556653
identification and characterization of a novel bacterial atp-sensitive k+ channel.five bacterial species that are most likely to have putative prokaryotic inward rectifier k(+) (kir) channels were selected by in silico sequence homology and membrane topology analyses with respect to the number of transmembrane domains (tms) and the presence of k(+) selectivity filter and/or atp binding sites in reference to rabbit heart inward rectifier k(+) channel (kir6.2). a dot blot assay with genomic dnas when probed with whole rabbit kir6.2 cdna further supported the in silico analysis ...201020571950
the novel two-component regulatory system bfisr regulates biofilm development by controlling the small rna rsmz through cafa.the formation of biofilms by the opportunistic pathogen pseudomonas aeruginosa is a developmental process governed by a novel signal transduction system composed of three two-component regulatory systems (tcss), bfisr, bfmsr, and mifsr. here, we show that bfisr-dependent arrest of biofilm formation coincided with reduced expression of genes involved in virulence, posttranslational/transcriptional modification, and rhl quorum sensing but increased expression of rhlab and the small regulatory rnas ...201020656909
characterization and pcr-based replicon typing of resistance plasmids in acinetobacter baumannii.acinetobacter baumannii is an opportunistic pathogen, especially in intensive care units, and multidrug-resistant isolates have increasingly been reported during the last decade. despite recent progress in knowledge of antibiotic resistance mechanisms in a. baumannii, little is known about the genetic factors driving isolates toward multidrug resistance. in the present study, the a. baumannii plasmids were investigated through the analysis and classification of plasmid replication systems and th ...201020660691
genetic and phenotypic diversity in burkholderia: contributions by prophage and phage-like elements.burkholderia species exhibit enormous phenotypic diversity, ranging from the nonpathogenic, soil- and water-inhabiting burkholderia thailandensis to the virulent, host-adapted mammalian pathogen b. mallei. genomic diversity is evident within burkholderia species as well. individual isolates of burkholderia pseudomallei and b. thailandensis, for example, carry a variety of strain-specific genomic islands (gis), including putative pathogenicity and metabolic islands, prophage-like islands, and pro ...201020667135
interkingdom signaling between pathogenic bacteria and caenorhabditis elegans.investigators have recently turned to the soil nematode caenorhabditis elegans as a small animal infection model to study infectious disease. to extrapolate findings concerning bacterial pathogenesis from non-mammals to mammals, virulence factors should be conserved in function, independent of the infection model. emerging from these studies is the observation that bacterial virulence regulatory networks function in a conserved manner across multiple hosts, including nematodes, mice and plants. ...201020667738
the chitinolytic activity of listeria monocytogenes egd is regulated by carbohydrates but also by the virulence regulator prfa.chitin, an insoluble polymer of n-acetyl-d-glucosamine (glcnac), is one of the most abundant carbohydrate polymers in marine and terrestrial environments. chitin hydrolysis by listeria monocytogenes depends on two chitinase-encoding genes, chia and chib, and the aim of this study was to investigate their regulation. chitin induces the expression of both chitinases in late exponential growth phase, and chia but not chib is furthermore induced by the monomer glcnac. furthermore, their expression i ...201020675445
construction of self-transmissible green fluorescent protein-based biosensor plasmids and their use for identification of n-acyl homoserine-producing bacteria in lake sediments.many bacteria utilize quorum sensing (qs) systems to communicate with each other by means of the production, release, and response to signal molecules. n-acyl homoserine lactone (ahl)-based qs systems are particularly widespread among the proteobacteria, in which they regulate various functions. it has become evident that ahls can also serve as signals for interspecies communication. however, knowledge on the impact of ahls for the ecology of bacteria in their natural habitat is scarce, due main ...201020675456
genome sequencing reveals widespread virulence gene exchange among human neisseria species.commensal bacteria comprise a large part of the microbial world, playing important roles in human development, health and disease. however, little is known about the genomic content of commensals or how related they are to their pathogenic counterparts. the genus neisseria, containing both commensal and pathogenic species, provides an excellent opportunity to study these issues. we undertook a comprehensive sequencing and analysis of human commensal and pathogenic neisseria genomes. commensals h ...201020676376
phenotypic and physiological alterations by heterologous acylhomoserine lactone synthase expression in pseudomonas putida.many bacteria harbour an incomplete quorum-sensing (qs) system, whereby they possess luxr homologues without the qs acylhomoserine lactone (ahl) synthase, which is encoded by a luxi homologue. an artificial ahl-producing plasmid was constructed using a cvii gene encoding the c6-ahl [n-hexanoyl homoserine lactone (hhl)] synthase from chromobacterium violaceum, and was introduced successfully into both the wild-type and a ppor (luxr homologue) mutant of pseudomonas putida. our data provide evidenc ...201020705668
evaluation of anti-quorum-sensing activity of edible plants and fruits through inhibition of the n-acyl-homoserine lactone system in chromobacterium violaceum and pseudomonas aeruginosa.to find out an alternative strategy to antibiotic usage against bacterial infection.201020720417
the chlamydial type iii secretion mechanism: revealing cracks in a tough nut.present-day members of the chlamydiaceae contain parasitic bacteria that have been co-evolving with their eukaryotic hosts over hundreds of millions of years. likewise, a type iii secretion system encoded within all genomes has been refined to complement the unique obligate intracellular niche colonized so successfully by chlamydia spp. all this adaptation has occurred in the apparent absence of the horizontal gene transfer responsible for creating the wide range of diversity in other gram-negat ...201021738522
screening of certain medicinal plants from india for their anti-quorum sensing activity.discovery of quorum sensing (qs) system to coordinate virulence and biofilm formation in bacterial pathogens has triggered search for safe, stable and non-toxic anti-qs compounds from natural products. ethanolic extracts of 24 indian medicinal plants were tested by agar well and disc diffusion assay for anti-qs activity using chromobacterium violaceum (cv12472 and cvo26) reporter strains. ahl from c. violaceum cv31532 was isolated and partially purified for its use in cvo26 based bioassay. effec ...201021250604
chromobacterium violaceum and its important metabolites--review.c. violaceum appeared as important bacterium in different applications and mainly these aspects are related to the production of violacein. this review discusses the last reports on biosynthetic pathways, production, genetic aspects, biological activities, pathological effects, antipathogenic screening through quorum sensing, environmental effects and the products of c. violaceum with industrial interest. an important discussion is on biological applications in medicine and as industrial product ...201021253897
distribution analysis of hydrogenases in surface waters of marine and freshwater environments.surface waters of aquatic environments have been shown to both evolve and consume hydrogen and the ocean is estimated to be the principal natural source. in some marine habitats, h(2) evolution and uptake are clearly due to biological activity, while contributions of abiotic sources must be considered in others. until now the only known biological process involved in h(2) metabolism in marine environments is nitrogen fixation.201021079771
cross-species induction of antimicrobial compounds, biosurfactants and quorum-sensing inhibitors in tropical marine epibiotic bacteria by pathogens and biofouling microorganisms.enhancement or induction of antimicrobial, biosurfactant, and quorum-sensing inhibition property in marine bacteria due to cross-species and cross-genera interactions was investigated. four marine epibiotic bacteria (bacillus sp. s3, b. pumilus s8, b. licheniformis d1, and serratia marcescens v1) displaying antimicrobial activity against pathogenic or biofouling fungi (candida albicans ca and yarrowia lipolytica yl), and bacteria (pseudomonas aeruginosa pa and bacillus pumilus bp) were chosen fo ...201021086131
volatile-mediated killing of arabidopsis thaliana by bacteria is mainly due to hydrogen cyanide.the volatile-mediated impact of bacteria on plant growth is well documented, and contrasting effects have been reported ranging from 6-fold plant promotion to plant killing. however, very little is known about the identity of the compounds responsible for these effects or the mechanisms involved in plant growth alteration. we hypothesized that hydrogen cyanide (hcn) is a major factor accounting for the observed volatile-mediated toxicity of some strains. using a collection of environmental and c ...201021115704
volatile-mediated killing of arabidopsis thaliana by bacteria is mainly due to hydrogen cyanide.the volatile-mediated impact of bacteria on plant growth is well documented, and contrasting effects have been reported ranging from 6-fold plant promotion to plant killing. however, very little is known about the identity of the compounds responsible for these effects or the mechanisms involved in plant growth alteration. we hypothesized that hydrogen cyanide (hcn) is a major factor accounting for the observed volatile-mediated toxicity of some strains. using a collection of environmental and c ...201021115704
immense essence of excellence: marine microbial bioactive compounds.oceans have borne most of the biological activities on our planet. a number of biologically active compounds with varying degrees of action, such as anti-tumor, anti-cancer, anti-microtubule, anti-proliferative, cytotoxic, photo protective, as well as antibiotic and antifouling properties, have been isolated to date from marine sources. the marine environment also represents a largely unexplored source for isolation of new microbes (bacteria, fungi, actinomycetes, microalgae-cyanobacteria and di ...201021116414
the dimeric sos mutagenesis protein umud is active as a monomer.the homodimeric umud gene products play key roles in regulating the cellular response to dna damage in escherichia coli. umud(2) is composed of 139-amino acid subunits and is up-regulated as part of the sos response. subsequently, damage-induced reca·ssdna nucleoprotein filaments mediate the slow self-cleavage of the n-terminal 24-amino acid arms yielding umud'(2). umud(2) and umud'(2) make a number of distinct protein-protein contacts that both prevent and facilitate mutagenic translesion synth ...201021118802
the dimeric sos mutagenesis protein umud is active as a monomer.the homodimeric umud gene products play key roles in regulating the cellular response to dna damage in escherichia coli. umud(2) is composed of 139-amino acid subunits and is up-regulated as part of the sos response. subsequently, damage-induced reca·ssdna nucleoprotein filaments mediate the slow self-cleavage of the n-terminal 24-amino acid arms yielding umud'(2). umud(2) and umud'(2) make a number of distinct protein-protein contacts that both prevent and facilitate mutagenic translesion synth ...201021118802
three motab stator gene products in bdellovibrio bacteriovorus contribute to motility of a single flagellum during predatory and prey-independent growth.the predatory bacterium bdellovibrio bacteriovorus uses flagellar motility to locate regions rich in gram-negative prey bacteria, colliding and attaching to prey and then ceasing flagellar motility. prey are then invaded to form a "bdelloplast" in a type iv pilus-dependent process, and prey contents are digested, allowing bdellovibrio growth and septation. after septation, bdellovibrio flagellar motility resumes inside the prey bdelloplast prior to its lysis and escape of bdellovibrio progeny. b ...201021148728
three motab stator gene products in bdellovibrio bacteriovorus contribute to motility of a single flagellum during predatory and prey-independent growth.the predatory bacterium bdellovibrio bacteriovorus uses flagellar motility to locate regions rich in gram-negative prey bacteria, colliding and attaching to prey and then ceasing flagellar motility. prey are then invaded to form a "bdelloplast" in a type iv pilus-dependent process, and prey contents are digested, allowing bdellovibrio growth and septation. after septation, bdellovibrio flagellar motility resumes inside the prey bdelloplast prior to its lysis and escape of bdellovibrio progeny. b ...201021148728
gram-positive marine bacteria as a potential resource for the discovery of quorum sensing inhibitors.inhibitors of bacterial quorum sensing have been proposed as potentially novel therapeutics for the treatment of certain bacterial diseases. we recently reported a marine halobacillus salinus isolate that secretes secondary metabolites capable of quenching quorum sensing phenotypes in several gram-negative reporter strains. to investigate how widespread the production of such compounds may be in the marine bacterial environment, 332 gram-positive isolates from diverse habitats were tested for th ...201021152942
quorum quenching in cultivable bacteria from dense marine coastal microbial communities.acylhomoserine lactone (ahls)-mediated quorum-sensing (qs) processes seem to be common in the marine environment and among marine pathogenic bacteria, but no data are available on the prevalence of bacteria capable of interfering with qs in the sea, a process that has been generally termed 'quorum quenching' (qq). one hundred and sixty-six strains isolated from different marine dense microbial communities were screened for their ability to interfere with ahl activity. twenty-four strains (14.4%) ...201021155853
metagenomic analyses: past and future trends.metagenomics has revolutionized microbiology by paving the way for a cultivation-independent assessment and exploitation of microbial communities present in complex ecosystems. metagenomics comprising construction and screening of metagenomic dna libraries has proven to be a powerful tool to isolate new enzymes and drugs of industrial importance. so far, the majority of the metagenomically exploited habitats comprised temperate environments, such as soil and marine environments. recently, metage ...201021169428
metagenomic analyses: past and future trends.metagenomics has revolutionized microbiology by paving the way for a cultivation-independent assessment and exploitation of microbial communities present in complex ecosystems. metagenomics comprising construction and screening of metagenomic dna libraries has proven to be a powerful tool to isolate new enzymes and drugs of industrial importance. so far, the majority of the metagenomically exploited habitats comprised temperate environments, such as soil and marine environments. recently, metage ...201021169428
a novel cdsab operon is involved in the uptake of l-cysteine and participates in the pathogenesis of yersinia ruckeri.application of in vivo expression technology (ivet) to yersinia ruckeri, an important fish pathogen, allowed the identification of two adjacent genes that represent a novel bacterial system involved in the uptake and degradation of l-cysteine. analysis of the translational products of both genes showed permease domains (open reading frame 1 [orf1]) and amino acid position identities (orf2) with the l-cysteine desulfidase from methanocaldococcus jannaschii, a new type of enzyme involved in the br ...201021169490
a novel cdsab operon is involved in the uptake of l-cysteine and participates in the pathogenesis of yersinia ruckeri.application of in vivo expression technology (ivet) to yersinia ruckeri, an important fish pathogen, allowed the identification of two adjacent genes that represent a novel bacterial system involved in the uptake and degradation of l-cysteine. analysis of the translational products of both genes showed permease domains (open reading frame 1 [orf1]) and amino acid position identities (orf2) with the l-cysteine desulfidase from methanocaldococcus jannaschii, a new type of enzyme involved in the br ...201021169490
novel pan-genomic analysis approach in target selection for multiplex pcr identification and detection of burkholderia pseudomallei, burkholderia thailandensis, and burkholderia cepacia complex species: a proof-of-concept study.burkholderia pseudomallei, burkholderia thailandensis, and the burkholderia cepacia complex differ greatly in pathogenicity and epidemiology. yet, they are occasionally misidentified by biochemical profiling, and even 16s rrna gene sequencing may not offer adequate discrimination between certain species groups. using the 23 b. pseudomallei, four b. thailandensis, and 16 b. cepacia complex genome sequences available, we identified gene targets specific to each of them (a tat domain protein, a 70- ...201021177905
new insights into the genetic organization of the fk228 biosynthetic gene cluster in chromobacterium violaceum no. 968.the biosynthetic gene cluster of fk228, an fda-approved anticancer natural product, was identified and sequenced previously. the genetic organization of this gene cluster has now been delineated through systematic gene deletion and transcriptional analysis. as a result, the gene cluster is redefined to contain 12 genes: depa through depj, depm, and a newly identified pathway regulatory gene, depr.201021183645
reconstitution of the fk228 biosynthetic pathway reveals cross talk between modular polyketide synthases and fatty acid synthase.functional cross talk between fatty acid biosynthesis and secondary metabolism has been discovered in several cases in microorganisms; none of them, however, involves a modular biosynthetic enzyme. previously, we reported a hybrid modular nonribosomal peptide synthetase (nrps)-polyketide synthase (pks) pathway for the biosynthesis of fk228 anticancer depsipeptide in chromobacterium violaceum strain 968. this pathway contains two pks modules on the depbc enzymes that lack a functional acyltransfe ...201021183648
histone deacetylase inhibitors in the treatment of hematological malignancies and solid tumors.the human genome is epigenetically organized through a series of modifications to the histone proteins that interact with the dna. in cancer, many of the proteins that regulate these modifications can be altered in both function and expression. one example of this is the family of histone deacetylases (hdacs), which as their name implies remove acetyl groups from the histone proteins, allowing for more condensed nucleosomal structure. hdacs have increased expression in cancer and are also believ ...201021188171
histone deacetylase inhibitors in the treatment of hematological malignancies and solid tumors.the human genome is epigenetically organized through a series of modifications to the histone proteins that interact with the dna. in cancer, many of the proteins that regulate these modifications can be altered in both function and expression. one example of this is the family of histone deacetylases (hdacs), which as their name implies remove acetyl groups from the histone proteins, allowing for more condensed nucleosomal structure. hdacs have increased expression in cancer and are also believ ...201021188171
enterobacteriaceae associated with eggs of podocnemis expansa and podocnemis unifilis (testudines:chelonia) in nonpolluted sites of national park of araguaia plains, brazil.fertile eggs of podocnemis expansa and podocnemis unifilis were investigated for the presence of enterobacteria, as these two endangered species have the potential for conservation measures that include egg transfer. knowledge of normal microflora associated with turtles and turtle eggs would help effectively manage the transfer of these eggs among institutions. thirty eggs of each species were collected, aseptically transferred, cracked inside plastic bags containing tetrathionate broth, and sp ...201021370647
medicinal chemistry as a conduit for the modulation of quorum sensing. 201020669927
thiol dioxygenases: unique families of cupin proteins.proteins in the cupin superfamily have a wide range of biological functions in archaea, bacteria and eukaryotes. although proteins in the cupin superfamily show very low overall sequence similarity, they all contain two short but partially conserved cupin sequence motifs separated by a less conserved intermotif region that varies both in length and amino acid sequence. furthermore, these proteins all share a common architecture described as a six-stranded β-barrel core, and this canonical cupin ...201020195658
thiol dioxygenases: unique families of cupin proteins.proteins in the cupin superfamily have a wide range of biological functions in archaea, bacteria and eukaryotes. although proteins in the cupin superfamily show very low overall sequence similarity, they all contain two short but partially conserved cupin sequence motifs separated by a less conserved intermotif region that varies both in length and amino acid sequence. furthermore, these proteins all share a common architecture described as a six-stranded β-barrel core, and this canonical cupin ...201020195658
pseudomonas aeruginosa biofilm inactivation: decreased cell culturability, adhesiveness to surfaces, and biofilm thickness upon high-pressure nonthermal plasma treatment.bacterial biofilms are more resilient to standard killing methods than free-living bacteria. pseudomonas aeruginosa pao1 biofilms grown on borosilicate coupons were treated with gas-discharge plasma for various exposure times. almost 100% of the cells were inactivated after a 5-min plasma exposure. atomic force microscopy was used to image the biofilms and study their micromechanical properties. results show that the adhesiveness to borosilicate and the thickness of the pseudomonas biofilms are ...201021544254
two new families of the ftsz-tubulin protein superfamily implicated in membrane remodeling in diverse bacteria and archaea.several recent discoveries reveal unexpected versatility of the bacterial and archaeal cytoskeleton systems that are involved in cell division and other processes based on membrane remodeling. here we apply methods for distant protein sequence similarity detection, phylogenetic approaches, and genome context analysis to described two previously unnoticed families of the ftsz-tubulin superfamily. one of these families is limited in its spread to proteobacteria whereas the other is represented in ...201020459678
enzymatic processing of fumiquinazoline f: a tandem oxidative-acylation strategy for the generation of multicyclic scaffolds in fungal indole alkaloid biosynthesis.aspergillus fumigatus af293 is a known producer of quinazoline natural products, including the antitumor fumiquinazolines, of which the simplest member is fumiquinazoline f (fqf) with a 6-6-6 tricyclic core derived from anthranilic acid, tryptophan, and alanine. fqf is the proposed biological precursor to fumiquinazoline a (fqa) in which the pendant indole side chain has been modified via oxidative coupling of an additional molecule of alanine, yielding a fused 6-5-5 imidazoindolone. we recently ...201020804163
mediators of lipid a modification, rna degradation, and central intermediary metabolism facilitate the growth of legionella pneumophila at low temperatures.legionella pneumophila is an aquatic bacterium that is also the agent of legionnaires' disease pneumonia. since l. pneumophila is transmitted directly from the environment to the lung, it is important to understand how legionellae survive at low temperatures. to identify genes that are needed for l. pneumophila growth at low temperature, we screened a population of mutagenized legionellae for strains that are specifically impaired for growth at 17 degrees c. from the 7,400 mutants tested, 11 dis ...201019768502
mediators of lipid a modification, rna degradation, and central intermediary metabolism facilitate the growth of legionella pneumophila at low temperatures.legionella pneumophila is an aquatic bacterium that is also the agent of legionnaires' disease pneumonia. since l. pneumophila is transmitted directly from the environment to the lung, it is important to understand how legionellae survive at low temperatures. to identify genes that are needed for l. pneumophila growth at low temperature, we screened a population of mutagenized legionellae for strains that are specifically impaired for growth at 17 degrees c. from the 7,400 mutants tested, 11 dis ...201019768502
structural insight into the mechanism of c-di-gmp hydrolysis by eal domain phosphodiesterases.cyclic diguanylate (or bis-(3'-5') cyclic dimeric guanosine monophosphate; c-di-gmp) is a ubiquitous second messenger that regulates diverse cellular functions, including motility, biofilm formation, cell cycle progression, and virulence in bacteria. in the cell, degradation of c-di-gmp is catalyzed by highly specific eal domain phosphodiesterases whose catalytic mechanism is still unclear. here, we purified 13 eal domain proteins from various organisms and demonstrated that their catalytic acti ...201020691189
single turnover kinetics of tryptophan hydroxylase: evidence for a new intermediate in the reaction of the aromatic amino acid hydroxylases.tryptophan hydroxylase (trph) uses a non-heme mononuclear iron center to catalyze the tetrahydropterin-dependent hydroxylation of tryptophan to 5-hydroxytryptophan. the reactions of the trph.fe(ii), trph.fe(ii).tryptophan, trph.fe(ii).6meph(4).tryptophan, and trph.fe(ii).6meph(4).phenylalanine complexes with o(2) were monitored by stopped-flow absorbance spectroscopy and rapid quench methods. the second-order rate constant for the oxidation of trph.fe(ii) has a value of 104 m(-1) s(-1) irrespect ...201020687613
macrocyclic histone deacetylase inhibitors.histone deacetylase inhibitors (hdaci) are an emerging class of novel anti-cancer drugs that cause growth arrest, differentiation, and apoptosis of tumor cells. in addition, they have shown promise as anti-parasitic, anti-neurodegenerative, anti-rheumatologic and immunosuppressant agents. to date, several structurally distinct small molecule hdaci have been reported including aryl hydroxamates, benzamides, short-chain fatty acids, electrophilic ketones, and macrocyclic peptides. macrocyclic hdac ...201020536416
structural basis of acyl-homoserine lactone-dependent signaling. 201021125993
structural basis of acyl-homoserine lactone-dependent signaling. 201021125993
beta-lactam antibiotics: from antibiosis to resistance and bacteriology.this review focuses on the era of antibiosis that led to a better understanding of bacterial morphology, in particular the cell wall component peptidoglycan. this is an effort to take readers on a tour de force from the concept of antibiosis, to the serendipity of antibiotics, evolution of beta-lactam development, and the molecular biology of antibiotic resistance. these areas of research have culminated in a deeper understanding of microbiology, particularly in the area of bacterial cell wall s ...201020041868
new antiseptic peptides to protect against endotoxin-mediated shock.systemic bacterial infections are associated with high mortality. the access of bacteria or constituents thereof to systemic circulation induces the massive release of immunomodulatory mediators, ultimately causing tissue hypoperfusion and multiple-organ failure despite adequate antibiotic treatment. lipid a, the "endotoxic principle" of bacterial lipopolysaccharide (lps), is one of the major bacterial immunostimuli. here we demonstrate the biological efficacy of rationally designed new syntheti ...201020606063
synthesis and evaluation of novel bis[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles as potent antimicrobial agents.a series of novel bis[4-methoxy-3-(6-aryl[1,2,4]triazolo[3,4-b][1,3,4]thiadiazol)phenyl]methanes 5a-l has been synthesized and characterized via ir, 1h nmr, 13c nmr, ms and elemental analyses. all the newly synthesized compounds were screened for their antibacterial activity against bacillus subtilis, bacillus sphaericu, staphylococcus aureus, pseudomonas aeruginosa, klobsinella aerogenes and chromobacterium violaceum and antifungal activity against candida albicans, aspergillus fumigatus, trich ...201024061822
malyngolide from the cyanobacterium lyngbya majuscula interferes with quorum sensing circuitry.extracts of several cyanobacterial species collected from different marine and estuarine locations predominately in florida (usa), with one sample each from belize and oman, were screened for their ability to disrupt quorum sensing (qs) in the reporter strain chromobacterium violaceum cv017. inhibitory activities were detected in the ethyl acetate : methanol (1:1) extracts of several lyngbya spp., and extracts of lyngbya majuscula contained the strongest qs inhibitory activities. extracts of l. ...201023766278
a fatal case of pulmonary chromobacterium violaceum infection in an adult.chromobacterium violaceum is a gram negative, facultative anaerobic coccobacillus. human infections are rare and usually occur after exposure to contaminated soil or water. infections can present with fulminant septicemia, multiple abscesses and rapidly spreading soft tissue infections. here we present a fatal case of pulmonary chromobacterium violaceum infection following aspiration of drain water. treatment with fluroquinolones in combination with either co-trimoxazole or amikacin has been des ...201023756802
enterobacteriaceae in mouth and cloaca of podocnemis expansa and p. unifilis (testudines: chelonia) populations of national park of araguaia plains, brazil.shigella flexnerii and escherichia coli were the most frequent gram-negative bacteria found in the mouth cavity and cloacae of the turtles podocnemis expansa and p. unifilis on beaches in the national park of araguaia, brazil. reptiles are known as salmonella carriers, despite rarely isolated in these turtles.201124031664
the promise of bacteriophage therapy for burkholderia cepacia complex respiratory infections.in recent times, increased attention has been given to evaluating the efficacy of phage therapy, especially in scenarios where the bacterial infectious agent of interest is highly antibiotic resistant. in this regard, phage therapy is especially applicable to infections caused by the burkholderia cepacia complex (bcc) since members of the bcc are antibiotic pan-resistant. current studies in bcc phage therapy are unique from many other avenues of phage therapy research in that the investigation i ...201122919592
the promise of bacteriophage therapy for burkholderia cepacia complex respiratory infections.in recent times, increased attention has been given to evaluating the efficacy of phage therapy, especially in scenarios where the bacterial infectious agent of interest is highly antibiotic resistant. in this regard, phage therapy is especially applicable to infections caused by the burkholderia cepacia complex (bcc) since members of the bcc are antibiotic pan-resistant. current studies in bcc phage therapy are unique from many other avenues of phage therapy research in that the investigation i ...201122919592
extreme antimicrobial peptide and polymyxin b resistance in the genus burkholderia.cationic antimicrobial peptides and polymyxins are a group of naturally occurring antibiotics that can also possess immunomodulatory activities. they are considered a new source of antibiotics for treating infections by bacteria that are resistant to conventional antibiotics. members of the genus burkholderia, which includes various human pathogens, are inherently resistant to antimicrobial peptides. the resistance is several orders of magnitude higher than that of other gram-negative bacteria s ...201122919572
extraction, purification and identification of bacterial signal molecules based on n-acyl homoserine lactones.bacteria possess an extraordinary repertoire for intercellular communication and social behaviour. this repertoire for bacterial communication, termed as quorum sensing (qs), depends on specific diffusible signal molecules. there are many different kinds of signal molecules in the bacterial community. among those signal molecules, n-acyl homoserine lactones (hsls, in other publications also referred to as ahls, acy-hsls etc.) are often employed as qs signal molecules for many gram-negative bacte ...201121375695
structure-based insights into the catalytic power and conformational dexterity of peroxiredoxins.peroxiredoxins (prxs), some of nature's dominant peroxidases, use a conserved cys residue to reduce peroxides. they are highly expressed in organisms from all kingdoms, and in eukaryotes they participate in hydrogen peroxide signaling. seventy-two prx structures have been determined that cover much of the diversity of the family. we review here the current knowledge and show that prxs can be effectively classified by a structural/evolutionary organization into six subfamilies followed by specifi ...201120969484
proteomics analysis of the effects of cyanate on chromobacterium violaceum metabolism.chromobacterium violaceum is a gram-negative betaproteobacterium that has been isolated from various brazilian ecosystems. its genome contains the cyn operon, which gives it the ability to metabolize highly toxic cyanate into ammonium and carbon dioxide. we used a proteomics approach to investigate the effects of cyanate on the metabolism of this bacterium. the proteome of cells grown with and without cyanate was compared on 2-d gels. differential spots were digested and identified by mass spect ...201124710289
anaerobiosis-induced loss of cytotoxicity is due to inactivation of quorum sensing in pseudomonas aeruginosa.pseudomonas aeruginosa, an opportunistic pathogen of clinical importance, causes chronic airway infections in patients with cystic fibrosis (cf). current literature suggests that pockets with reduced oxygen tension exist in the cf airway mucus. however, virulence features of this opportunistic pathogen under such conditions are largely unknown. cell-free supernatant of the standard laboratory p. aeruginosa strain pao1 obtained from anaerobic culture, but not aerobic culture, failed to kill a549 ...201121555402
Burkholderia cenocepacia BC2L-C is a super lectin with dual specificity and proinflammatory activity.Lectins and adhesins are involved in bacterial adhesion to host tissues and mucus during early steps of infection. We report the characterization of BC2L-C, a soluble lectin from the opportunistic pathogen Burkholderia cenocepacia, which has two distinct domains with unique specificities and biological activities. The N-terminal domain is a novel TNF-a-like fucose-binding lectin, while the C-terminal part is similar to a superfamily of calcium-dependent bacterial lectins. The C-terminal domain d ...201121909279
annotation of protein domains reveals remarkable conservation in the functional make up of proteomes across superkingdoms.the functional repertoire of a cell is largely embodied in its proteome, the collection of proteins encoded in the genome of an organism. the molecular functions of proteins are the direct consequence of their structure and structure can be inferred from sequence using hidden markov models of structural recognition. here we analyze the functional annotation of protein domain structures in almost a thousand sequenced genomes, exploring the functional and structural diversity of proteomes. we find ...201124710297
Sharing of quorum-sensing signals and role of interspecies communities in a bacterial plant disease.Pathogenic bacteria interact not only with the host organism but most probably also with the resident microbial flora. In the knot disease of the olive tree (Olea europaea), the causative agent is the bacterium Pseudomonas savastanoi pv. savastanoi (Psv). Two bacterial species, namely Pantoea agglomerans and Erwinia toletana, which are not pathogenic and are olive plant epiphytes and endophytes, have been found very often to be associated with the olive knot. We identified the chemical signals t ...201121677694
Draft genome sequence of the biocontrol bacterium Chromobacterium sp. strain C-61.Chromobacterium sp. strain C-61 is a plant-associated bacterium with proven capacities to suppress plant diseases. Here, we report the draft genome sequence and automatic annotation of strain C-61. A comparison of this sequence to the sequenced genome of Chromobacterium violaceum ATCC 12472 indicates the novelty of C-61 and a subset of gene functions that may be related to its biocontrol activities.201122072653
Histone deacetylase inhibitors from Burkholderia thailandensis.Bioactivity-guided fractionation of an extract of Burkholderia thailandensis led to the isolation and identification of a new cytotoxic depsipeptide and its dimer. Both compounds potently inhibited the function of histone deacetylases 1 and 4. The monomer, spiruchostatin C (2), was tested side by side with the clinical depsipeptide FK228 (1, Istodax, romidepsin) in a murine hollow fiber assay consisting of 12 implanted tumor cell lines. Spiruchostatin C (2) showed good activity toward LOX IMVI ...201121967146
glygly-cterm and rhombosortase: a c-terminal protein processing signal in a many-to-one pairing with a rhomboid family intramembrane serine protease.the rhomboid family of serine proteases occurs in all domains of life. its members contain at least six hydrophobic membrane-spanning helices, with an active site serine located deep within the hydrophobic interior of the plasma membrane. the model member glpg from escherichia coli is heavily studied through engineered mutant forms, varied model substrates, and multiple x-ray crystal studies, yet its relationship to endogenous substrates is not well understood. here we describe an apparent membr ...201122194940
chromobacterium violaceum infection: a clinical review of an important but neglected infection.increasing reported cases with chrombacterium violaceum infection has been noticed in recent decades. it is noteworthy for its difficult-to-treat entity characterized by a high frequency of sepsis, easily distantant metastasis, multidrug-resistance, and frequent relapse, and high mortality rate.201122036134
identification of a new gene required for the biosynthesis of rhodoquinone in rhodospirillum rubrum.rhodoquinone (rq) is a required cofactor for anaerobic respiration in rhodospirillum rubrum, and it is also found in several helminth parasites that utilize a fumarate reductase pathway. rq is an aminoquinone that is structurally similar to ubiquinone (q), a polyprenylated benzoquinone used in the aerobic respiratory chain. rq is not found in humans or other mammals, and therefore inhibition of its biosynthesis may provide a novel anti-parasitic drug target. to identify a gene specifically requi ...201122194448
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