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Berlin Brandenburg

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  • MEDLINE/PubMed (NLM)  (54)
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  • 1
    Language: English
    In: Journal of bacteriology, 01 February 2018, Vol.200(3)
    Description: Attachment is essential for microorganisms to establish interactions with both biotic and abiotic surfaces. Stable attachment of to surfaces requires an adhesive polysaccharide holdfast, but the exact composition of the holdfast is unknown. The holdfast is anchored to the cell envelope by outer membrane proteins HfaA, HfaB, and HfaD. oldast nchor gene mutations result in holdfast shedding and reduced cell adherence. Translocation of HfaA and HfaD to the cell surface requires HfaB. The Wzx homolog HfsF is predicted to be a bacterial polysaccharide flippase. An deletion significantly reduced the amount of holdfast produced per cell and slightly reduced adherence. A Δ Δ double mutant was completely deficient in adherence. A suppressor screen that restored adhesion in the Δ Δ mutant identified mutations in three genes: , , and Both WbqV and RfbB belong to a family of nucleoside-diphosphate epimerases, and RmlA has similarity to nucleotidyltransferases. The loss of or in the Δ Δ mutant reduced holdfast shedding but did not restore holdfast synthesis to parental levels. Loss of or did not restore adherence to a Δ mutant but did restore adherence and holdfast anchoring to a Δ mutant, confirming that suppression occurs through restoration of holdfast anchoring. The adherence and holdfast anchoring of a Δ mutant could be restored by or mutation, but such mutations could not suppress these phenotypes in the Δ mutant. We hypothesize that HfaB plays an additional role in holdfast anchoring or helps to translocate an unknown factor that is important for holdfast anchoring. Biofilm formation results in increased resistance to both environmental stresses and antibiotics. requires an adhesive holdfast for permanent attachment and biofilm formation, but the exact mechanism of polysaccharide anchoring to the cell and the holdfast composition are unknown. Here we identify novel polysaccharide genes that affect holdfast anchoring to the cell. We identify a new role for the holdfast anchor protein HfaB. This work increases our specific knowledge of the polysaccharide adhesin involved in attachment and the general knowledge regarding production and anchoring of polysaccharide adhesins by bacteria. This work also explores the interactions between different polysaccharide biosynthesis and secretion systems in bacteria.
    Keywords: Caulobacter ; Adherence ; Holdfast ; Polysaccharides ; Mutation ; Adhesins, Bacterial -- Genetics ; Bacterial Proteins -- Genetics ; Caulobacter Crescentus -- Genetics ; Nucleotides -- Genetics ; Polysaccharides, Bacterial -- Genetics ; Sugars -- Metabolism
    ISSN: 00219193
    E-ISSN: 1098-5530
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  • 2
    Language: English
    In: PLoS One, CA: Public Library of Science
    Description: This article explores the interrelationship between the urinary microbiota and host antimicrobial peptides as mechanisms for urinary tract infection risk.
    Keywords: Resident Bacterial Communities ; Host Antimicrobial Peptides ; Urinary Tract Infection
    ISSN: 19326203
    E-ISSN: 19326203
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  • 3
    Language: English
    In: PLoS One, San Francisco: Public Library of Science
    Description: Article discussing the microbial communities in male first catch urine and how these are highly similar to those paired in urethral swab specimens.
    Keywords: Microbials ; Bacteria ; Urine
    ISSN: 19326203
    E-ISSN: 19326203
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  • 4
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 18 April 2017, Vol.114(16), pp.4237-4242
    Description: (Nm) clonal complex 11 (cc11) lineage is a hypervirulent pathogen responsible for outbreaks of invasive meningococcal disease, including among men who have sex with men, and is increasingly associated with urogenital infections. Recently, clusters of Nm urethritis have emerged primarily among heterosexual males in the United States. We determined that nonencapsulated meningococcal isolates from an ongoing Nm urethritis outbreak among epidemiologically unrelated men in Columbus, Ohio, are linked to increased Nm urethritis cases in multiple US cities, including Atlanta and Indianapolis, and that they form a unique clade (the US Nm urethritis clade, US_NmUC). The isolates belonged to the cc11 lineage 11.2/ET-15 with fine type of PorA P1.5-1, 10-8; FetA F3-6; PorB 2-2 and express a unique FHbp allele. A common molecular fingerprint of US_NmUC isolates was an IS1301 element in the intergenic region separating the capsule operons and adjacent deletion of and a part of , encoding the serogroup C capsule polymerase. This resulted in the loss of encapsulation and intrinsic lipooligosaccharide sialylation that may promote adherence to mucosal surfaces. Furthermore, we detected an IS1301-mediated inversion of an ∼20-kb sequence near the locus. Surprisingly, these isolates had acquired by gene conversion the complete gonococcal denitrification B-A gene cassette, and strains grow well anaerobically. The cc11 US_NmUC isolates causing urethritis clusters in the United States may have adapted to a urogenital environment by loss of capsule and gene conversion of the - cassette promoting anaerobic growth.
    Keywords: Is1301 ; Neisseria Meningitidis ; Capsule ; Denitrification ; Meningococcal Urethritis ; Whole Genome Sequencing ; Meningitis, Meningococcal -- Epidemiology ; Neisseria Meningitidis -- Genetics
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 5
    In: The Journal of Bacteriology, 2008, Vol. 190(21), p.7219
    Description: Caulobacter crescentus cells adhere to surfaces by using an extremely strong polar adhesin called the holdfast. The polysaccharide component of the holdfast is comprised in part of oligomers of N-acetylglucosamine. The genes involved in the export of the holdfast polysaccharide and the anchoring of the holdfast to the cell were previously discovered. In this study, we identified a cluster of polysaccharide biosynthesis genes (hfsEFGH) directly adjacent to the holdfast polysaccharide export genes. Sequence analysis indicated that these genes are involved in the biosynthesis of the minimum repeat unit of the holdfast polysaccharide. HfsE is predicted to be a UDP-sugar lipid-carrier transferase, the glycosyltransferase that catalyzes the first step in polysaccharide biosynthesis. HfsF is predicted to be a flippase, HfsG is a glycosyltransferase, and HfsH is similar to a polysaccharide (chitin) deacetylase. In- frame hfsG and hfsH deletion mutants resulted in severe deficiencies both in surface adhesion and in binding to the holdfast-specific lectin wheat germ agglutinin. In contrast, hfsE and hfsF mutants exhibited nearly wild-type levels of adhesion and holdfast synthesis. We identified three paralogs to hfsE, two of which are redundant to hfsE for holdfast synthesis. We also identified a redundant paralog to the hfsC gene, encoding the putative polysaccharide polymerase, and present evidence that the hfsE and hfsC paralogs, together with the hfs genes, are absolutely required for proper holdfast synthesis. [PUBLICATION ]
    Keywords: Bacteria ; Bacteriology ; Carbohydrates ; Mutation ; Genes ; Catalysis;
    ISSN: 0021-9193
    ISSN: 00219193
    E-ISSN: 10985530
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  • 6
    Language: English
    In: PLoS ONE, 01 January 2014, Vol.9(10), p.e109677
    Description: Relationships between host and microbial diversity have important ecological and applied implications. Theory predicts that these relationships will depend on the spatio-temporal scale of the analysis and the niche breadth of the organisms in question, but representative data on host-microbial community assemblage in nature is lacking. We employed a natural gradient of rodent species richness and quantified bacterial communities in rodent blood at several hierarchical spatial scales to test the hypothesis that associations between host and microbial species diversity will be positive in communities dominated by organisms with broad niches sampled at large scales. Following pyrosequencing of rodent blood samples, bacterial communities were found to be comprised primarily of broad niche lineages. These communities exhibited positive correlations between host diversity, microbial diversity and the likelihood for rare pathogens at the regional scale but not at finer scales. These findings demonstrate how microbial diversity is affected by host diversity at different spatial scales and suggest that the relationships between host diversity and overall disease risk are not always negative, as the dilution hypothesis predicts.
    Keywords: Sciences (General)
    E-ISSN: 1932-6203
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  • 7
    Language: English
    In: PLoS ONE, 2012, Vol.7(5), p.e36298
    Description: Lactobacillus- dominated vaginal microbiotas are associated with reproductive health and STI resistance in women, whereas altered microbiotas are associated with bacterial vaginosis (BV), STI risk and poor reproductive outcomes. Putative vaginal taxa have been observed in male first-catch urine, urethral swab and coronal sulcus (CS) specimens but the significance of these observations is unclear. We used 16 S rRNA sequencing to characterize the microbiota of the CS and urine collected from 18 adolescent men over three consecutive months. CS microbiotas of most participants were more stable than their urine microbiotas and the composition of CS microbiotas were strongly influenced by circumcision. BV-associated taxa, including Atopobium , Megasphaera , Mobiluncus , Prevotella and Gemella , were detected in CS specimens from sexually experienced and inexperienced participants. In contrast, urine primarily contained taxa that were not abundant in CS specimens. Lactobacilllus and Streptococcus were major urine taxa but their abundance was inversely correlated. In contrast, Sneathia , Mycoplasma and Ureaplasma were only found in urine from sexually active participants. Thus, the CS and urine support stable and distinct bacterial communities. Finally, our results suggest that the penis and the urethra can be colonized by a variety of BV-associated taxa and that some of these colonizations result from partnered sexual activity.
    Keywords: Research Article ; Biology ; Medicine ; Public Health And Epidemiology ; Infectious Diseases ; Microbiology ; Urology
    E-ISSN: 1932-6203
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  • 8
    In: Molecular Microbiology, April 2010, Vol.76(2), pp.409-427
    Description: attachment is mediated by the holdfast, a complex of polysaccharide anchored to the cell by HfaA, HfaB and HfaD. We show that all three proteins are surface exposed outer membrane (OM) proteins. HfaA is similar to fimbrial proteins and assembles into a high molecular weight (HMW) form requiring HfaD, but not holdfast polysaccharide. The HfaD HMW form is dependent on HfaA but not on holdfast polysaccharide. We show that HfaA and HfaD form homomultimers and that they require HfaB for stability and OM translocation. All three proteins localize to the late pre‐divisional flagellar pole, remain at this pole in swarmer cells, and localize at the stalk tip after the stalk is synthesized at the same pole. Hfa protein localization requires the holdfast polysaccharide secretion proteins and the polar localization factor PodJ. An mutant is much more severely deficient in adherence and holdfast attachment than and mutants. An , double mutant phenocopies either single mutant, suggesting that HfaB is involved in holdfast attachment beyond secretion of HfaA and HfaD. We hypothesize that HfaB secretes HfaA and HfaD across the outer membrane, and the three proteins form a complex anchoring the holdfast to the stalk.
    Keywords: Proteins ; Polysaccharides;
    ISSN: 0950-382X
    E-ISSN: 1365-2958
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  • 9
    Language: English
    In: Journal of Bacteriology, 2012, Vol. 194(10), p.2646
    Description: Escherichia coli K-12 WcaJ and the Caulobacter crescentus HfsE, PssY, and PssZ enzymes are predicted to initiate the synthesis of colanic acid (CA) capsule and holdfast polysaccharide, respectively. These proteins belong to a prokaryotic family of membrane enzymes that catalyze the formation of a phosphoanhydride bond joining a hexose-1-phosphate with undecaprenyl phosphate (Und-P). In this study, in vivo complementation assays of an E. coli K-12 wcaJ mutant demonstrated that WcaJ and PssY can complement CA synthesis. Furthermore, WcaJ can restore holdfast production in C. crescentus. In vitro transferase assays demonstrated that both WcaJ and PssY utilize UDP-glucose but not UDP-galactose. However, in a strain of Salmonella enterica serovar Typhimurium deficient in the WbaP O antigen initiating galactosyltransferase, complementation with WcaJ or PssY resulted in O-antigen production. Gas chromatography-mass spectrometry (GC-MS) analysis of the lipopolysaccharide (LPS) revealed the attachment of both CA and O-antigen molecules to lipid A-core oligosaccharide (OS). Therefore, while UDP-glucose is the preferred substrate of WcaJ and PssY, these enzymes can also utilize UDP-galactose. This unexpected feature of WcaJ and PssY may help to map specific residues responsible for the nucleotide diphosphate specificity of these or similar enzymes. Also, the reconstitution of O-antigen synthesis in Salmonella, CA capsule synthesis in E. coli, and holdfast synthesis provide biological assays of high sensitivity to examine the sugar-1-phosphate transferase specificity of heterologous proteins. ; p. 2646-2657.
    Keywords: Gas-Chromatography-Mass Spectrometry ; Oligosaccharides ; Bioassays ; Glucose 1-Phosphate ; Lipopolysaccharides ; Salmonella Enterica Subsp. Enterica Serovar Typhimurium ; Transferases ; Proteins ; Escherichia Coli K12 ; Antigens ; Caulobacter Crescentus ; Mutants;
    ISSN: 1098-5530
    ISSN: 10985530
    ISSN: 00219193
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  • 10
    Language: English
    In: Journal of bacteriology, 01 August 2016, Vol.198(15), pp.2131-9
    Description: Intracellular bacterial pathogens in the family Chlamydiaceae are causes of human blindness, sexually transmitted disease, and pneumonia. Genetic dissection of the mechanisms of chlamydial pathogenicity has been hindered by multiple limitations, including the inability to inactivate genes that would prevent the production of elementary bodies. Many genes are also Chlamydia-specific genes, and chlamydial genomes have undergone extensive reductive evolution, so functions often cannot be inferred from homologs in other organisms. Conditional mutants have been used to study essential genes of many microorganisms, so we screened a library of 4,184 ethyl methanesulfonate-mutagenized Chlamydia trachomatis isolates for temperature-sensitive (TS) mutants that developed normally at physiological temperature (37°C) but not at nonphysiological temperatures. Heat-sensitive TS mutants were identified at a high frequency, while cold-sensitive mutants were less common. Twelve TS mutants were mapped using a novel markerless recombination approach, PCR, and genome sequencing. TS alleles of genes that play essential roles in other bacteria and chlamydia-specific open reading frames (ORFs) of unknown function were identified. Temperature-shift assays determined that phenotypes of the mutants manifested at distinct points in the developmental cycle. Genome sequencing of a larger population of TS mutants also revealed that the screen had not reached saturation. In summary, we describe the first approach for studying essential chlamydial genes and broadly applicable strategies for genetic mapping in Chlamydia spp. and mutants that both define checkpoints and provide insights into the biology of the chlamydial developmental cycle. Study of the pathogenesis of Chlamydia spp. has historically been hampered by a lack of genetic tools. Although there has been recent progress in chlamydial genetics, the existing approaches have limitations for the study of the genes that mediate growth of these organisms in cell culture. We used a genetic screen to identify conditional Chlamydia mutants and then mapped these alleles using a broadly applicable recombination strategy. Phenotypes of the mutants provide fundamental insights into unexplored areas of chlamydial pathogenesis and intracellular biology. Finally, the reagents and approaches we describe are powerful resources for the investigation of these organisms.
    Keywords: Recombination, Genetic ; Temperature ; Chlamydia Trachomatis -- Physiology
    ISSN: 00219193
    E-ISSN: 1098-5530
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