scholarly journals Uncovering Roles of Streptococcus gordonii SrtA-Processed Proteins in the Biofilm Lifestyle

2020 ◽  
Vol 203 (2) ◽  
pp. e00544-20
Author(s):  
Brittany L. Nairn ◽  
Grace T. Lee ◽  
Ashwani K. Chumber ◽  
Patrick R. Steck ◽  
Mahmoud O. Mire ◽  
...  
Keyword(s):  
Cell Wall ◽  
Biofilm Formation ◽  
Deletion Mutant ◽  
Ex Vivo ◽  
Sortase A ◽  
Cell Wall Proteins ◽  
Mutant Library ◽  
Rich Medium ◽  
Content Type ◽  
Markerless Deletion

ABSTRACTStreptococcus gordonii is a commensal oral organism. Harmless in the oral cavity, S. gordonii is an opportunistic pathogen. S. gordonii adheres to body surfaces using surface adhesive proteins (adhesins), which are critical to subsequent formation of biofilm communities. As in most Gram-positive bacteria, S. gordonii surface proteins containing the C-terminal LPXTG motif cleavage sequence are processed by sortase A (SrtA) to become covalently attached to the cell wall. To characterize the functional diversity and redundancy in the family of SrtA-processed proteins, an S. gordonii DL1 markerless deletion mutant library was constructed of each of the 26 putative SrtA-processed proteins. Each library member was evaluated for growth in rich medium, biofilm formation on plastic, saliva and salivary fractions, cell surface hydrophobicity (CSH), hemagglutination, and integration into an ex vivo plaque biofilm community. Library members were compared to the non-SrtA-processed adhesins AbpA and AbpB. While no major growth differences in rich medium were observed, many S. gordonii LPXTG/A proteins impacted biofilm formation on one or more of the substrates. Several mutants showed significant differences in hemagglutination, hydrophobicity, or fitness in the ex vivo plaque model. From the identification of redundant and unique functions in these in vitro and ex vivo systems, functional stratification among the LPXTG/A proteins is apparent.IMPORTANCES. gordonii interactions with its environment depend on the complement of cell wall proteins. A subset of these cell wall proteins requires processing by the enzyme sortase A (SrtA). The identification of SrtA-processed proteins and their functional characterization will help the community to better understand how S. gordonii engages with its surroundings, including other microbes, integrates into the plaque community, adheres to the tooth surface, and hematogenously disseminates to cause blood-borne infections. This study identified 26 putative SrtA-processed proteins through creation of a markerless deletion mutant library. The library was subject to functional screens that were chosen to better understand key aspects of S. gordonii physiology and pathogenesis.

scholarly journals Deletion Mutant Library for Investigation of Functional Outputs of Cyclic Diguanylate Metabolism in Pseudomonas aeruginosa PA14

2014 ◽  
Vol 80 (11) ◽  
pp. 3384-3393 ◽  
Author(s):  
Dae-Gon Ha ◽  
Megan E. Richman ◽  
George A. O'Toole
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Deletion Mutant ◽  
Deletion Mutants ◽  
Mutant Library ◽  
Potential Utility ◽  
Cyclic Diguanylate ◽  
Swarming Motility ◽  
Content Type ◽  
Swimming Motility

ABSTRACTWe constructed a library of in-frame deletion mutants targeting each gene inPseudomonas aeruginosaPA14 predicted to participate in cyclic di-GMP (c-di-GMP) metabolism (biosynthesis or degradation) to provide a toolkit to assist investigators studying c-di-GMP-mediated regulation by this microbe. We present phenotypic assessments of each mutant, including biofilm formation, exopolysaccharide (EPS) production, swimming motility, swarming motility, and twitch motility, as a means to initially characterize these mutants and to demonstrate the potential utility of this library.

scholarly journals Interplay between Antibiotic Efficacy and Drug-Induced Lysis Underlies Enhanced Biofilm Formation at Subinhibitory Drug Concentrations

2017 ◽  
Vol 62 (1) ◽  
Author(s):  
Wen Yu ◽  
Kelsey M. Hallinen ◽  
Kevin B. Wood
Keyword(s):  
Cell Wall ◽  
Biofilm Formation ◽  
Cell Lysis ◽  
Living Cells ◽  
Cell Wall Synthesis ◽  
Drug Induced ◽  
Trade Off ◽  
Content Type ◽  
Subinhibitory Concentrations ◽  
Antibiotic Efficacy

ABSTRACTSubinhibitory concentrations of antibiotics have been shown to enhance biofilm formation in multiple bacterial species. While antibiotic exposure has been associated with modulated expression of many biofilm-related genes, the mechanisms of drug-induced biofilm formation remain a focus of ongoing research efforts and may vary significantly across species. In this work, we investigate antibiotic-induced biofilm formation inEnterococcus faecalis, a leading cause of nosocomial infections. We show that biofilm formation is enhanced by subinhibitory concentrations of cell wall synthesis inhibitors but not by inhibitors of protein, DNA, folic acid, or RNA synthesis. Furthermore, enhanced biofilm is associated with increased cell lysis, increases in extracellular DNA (eDNA) levels, and increases in the density of living cells in the biofilm. In addition, we observe similar enhancement of biofilm formation when cells are treated with nonantibiotic surfactants that induce cell lysis. These findings suggest that antibiotic-induced biofilm formation is governed by a trade-off between drug toxicity and the beneficial effects of cell lysis. To understand this trade-off, we developed a simple mathematical model that predicts changes in antibiotic-induced biofilm formation due to external perturbations, and we verified these predictions experimentally. Specifically, we demonstrate that perturbations that reduce eDNA (DNase treatment) or decrease the number of living cells in the planktonic phase (a second antibiotic) decrease biofilm induction, while chemical inhibitors of cell lysis increase relative biofilm induction and shift the peak to higher antibiotic concentrations. Overall, our results offer experimental evidence linking cell wall synthesis inhibitors, cell lysis, increased eDNA levels, and biofilm formation inE. faecaliswhile also providing a predictive quantitative model that sheds light on the interplay between cell lysis and antibiotic efficacy in developing biofilms.

scholarly journals Homologous Recombination in Clostridioides difficile Mediates Diversification of Cell Surface Features and Transport Systems

mSphere ◽  
2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Hannah D. Steinberg ◽  
Evan S. Snitkin
Keyword(s):  
Cell Wall ◽  
Homologous Recombination ◽  
Sugar Transport ◽  
The United States ◽  
Strain Typing ◽  
Cell Wall Proteins ◽  
Genetic Loci ◽  
Content Type ◽  
Clostridioides Difficile ◽  
Host Pathogen

ABSTRACT Illness caused by the pathogen Clostridioides difficile is widespread and can range in severity from mild diarrhea to sepsis and death. Strains of C. difficile isolated from human infections exhibit great genetic diversity, leading to the hypothesis that the genetic background of the infecting strain at least partially determines a patient’s clinical course. However, although certain strains of C. difficile have been suggested to be associated with increased severity, strain typing alone has proved insufficient to explain infection severity. The limited explanatory power of strain typing has been hypothesized to be due to genetic variation within strain types, as well as genetic elements shared between strain types. Homologous recombination is an evolutionary mechanism that can result in large genetic differences between two otherwise clonal isolates, and also lead to convergent genotypes in distantly related strains. More than 400 C. difficile genomes were analyzed here to assess the effect of homologous recombination within and between C. difficile clades. Almost three-quarters of single nucleotide variants in the C. difficile phylogeny are predicted to be due to homologous recombination events. Furthermore, recombination events were enriched in genes previously reported to be important to virulence and host-pathogen interactions, such as flagella, cell wall proteins, and sugar transport and metabolism. Thus, by exploring the landscape of homologous recombination in C. difficile, we identified genetic loci whose elevated rates of recombination mediated diversification, making them strong candidates for being mediators of host-pathogen interaction in diverse strains of C. difficile. IMPORTANCE Infections with C. difficile result in up to half a million illnesses and tens of thousands of deaths annually in the United States. The severity of C. difficile illness is dependent on both host and bacterial factors. Studying the evolutionary history of C. difficile pathogens is important for understanding the variation in pathogenicity of these bacteria. This study examines the extent and targets of homologous recombination, a mechanism by which distant strains of bacteria can share genetic material, in hundreds of C. difficile strains and identifies hot spots of realized recombination events. The results of this analysis reveal the importance of homologous recombination in the diversification of genetic loci in C. difficile that are significant in its pathogenicity and host interactions, such as flagellar construction, cell wall proteins, and sugar transport and metabolism.

scholarly journals Slipped strand mispairing in the gene encoding sialidase NanH3 in Gardnerella spp

2020 ◽  
Author(s):  
Shakya P. Kurukulasuriya ◽  
Mo H. Patterson ◽  
Janet E. Hill
Keyword(s):  
Cell Wall ◽  
Biofilm Formation ◽  
Gene Sequence ◽  
Phase Variation ◽  
Cell Wall Proteins ◽  
Vaginal Microbiome ◽  
Gene Encoding ◽  
Reading Frame ◽  
Sialidase Activity ◽  
Mucosal Surfaces

AbstractCell wall proteins with sialidase activity are involved in carbohydrate assimilation, adhesion to mucosal surfaces, and biofilm formation. Gardnerella spp. inhabit the human vaginal microbiome and encode up to three sialidase enzymes, two of which are suspected to be cell wall associated. Here we demonstrate that the gene encoding extracellular sialidase NanH3 is found almost exclusively in G. piotii and closely related Gardnerella genome sp. 3, and its presence correlates with sialidase positive phenotype in a collection of 112 Gardnerella isolates. The nanH3 gene sequence includes a homopolymeric repeat of cytosines that varies in length within cell populations, indicating that this gene is subject to slipped-strand mispairing, a mechanisms of phase variation in bacteria. Variation in the length of the homopolymer sequence results in encoding of either the full length sialidase protein or truncated peptides lacking the sialidase domain due to introduction of reading-frame shifts and premature stop codons. Phase variation in NanH3 may be involved in immune evasion or modulation of adhesion to host epithelial cells, and formation of biofilms characteristic of the vaginal dysbiosis known as bacterial vaginosis.

scholarly journals The Transcription Factor SomA Synchronously Regulates Biofilm Formation and Cell Wall Homeostasis in Aspergillus fumigatus

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Yuan Chen ◽  
Francois Le Mauff ◽  
Yan Wang ◽  
Ruiyang Lu ◽  
Donald C. Sheppard ◽  
...  
Keyword(s):  
Cell Wall ◽  
Transcription Factor ◽  
Aspergillus Fumigatus ◽  
Biofilm Formation ◽  
Wall Stress ◽  
Fungal Cell ◽  
Glucan Synthase ◽  
Content Type ◽  
Cell Wall Stress ◽  
Chitin Synthases

ABSTRACT Polysaccharides are key components of both the fungal cell wall and biofilm matrix. Despite having distinct assembly and regulation pathways, matrix exopolysaccharide and cell wall polysaccharides share common substrates and intermediates in their biosynthetic pathways. It is not clear, however, if the biosynthetic pathways governing the production of these polysaccharides are cooperatively regulated. Here, we demonstrate that cell wall stress promotes production of the exopolysaccharide galactosaminogalactan (GAG)-depend biofilm formation in the major fungal pathogen of humans Aspergillus fumigatus and that the transcription factor SomA plays a crucial role in mediating this process. A core set of SomA target genes were identified by transcriptome sequencing and chromatin immunoprecipitation coupled to sequencing (ChIP-Seq). We identified a novel SomA-binding site in the promoter regions of GAG biosynthetic genes agd3 and ega3, as well as its regulators medA and stuA. Strikingly, this SomA-binding site was also found in the upstream regions of genes encoding the cell wall stress sensors, chitin synthases, and β-1,3-glucan synthase. Thus, SomA plays a direct regulation of both GAG and cell wall polysaccharide biosynthesis. Consistent with these findings, SomA is required for the maintenance of normal cell wall architecture and compositions in addition to its function in biofilm development. Moreover, SomA was found to globally regulate glucose uptake and utilization, as well as amino sugar and nucleotide sugar metabolism, which provides precursors for polysaccharide synthesis. Collectively, our work provides insight into fungal adaptive mechanisms in response to cell wall stress where biofilm formation and cell wall homeostasis were synchronously regulated. IMPORTANCE The cell wall is essential for fungal viability and is absent from human hosts; thus, drugs disrupting cell wall biosynthesis have gained more attention. Caspofungin is a member of a new class of clinically approved echinocandin drugs to treat invasive aspergillosis by blocking β-1,3-glucan synthase, thus damaging the fungal cell wall. Here, we demonstrate that caspofungin and other cell wall stressors can induce galactosaminogalactan (GAG)-dependent biofilm formation in the human pathogen Aspergillus fumigatus. We further identified SomA as a master transcription factor playing a dual role in both biofilm formation and cell wall homeostasis. SomA plays this dual role by direct binding to a conserved motif upstream of GAG biosynthetic genes and genes involved in cell wall stress sensors, chitin synthases, and β-1,3-glucan synthase. Collectively, these findings reveal a transcriptional control pathway that integrates biofilm formation and cell wall homeostasis and suggest SomA as an attractive target for antifungal drug development.

scholarly journals Na+/H+Antiport Is Essential for Yersinia pestis Virulence

2013 ◽  
Vol 81 (9) ◽  
pp. 3163-3172 ◽  
Author(s):  
Yusuke Minato ◽  
Amit Ghosh ◽  
Wyatt J. Faulkner ◽  
Erin J. Lind ◽  
Sara Schesser Bartra ◽  
...  
Keyword(s):  
Yersinia Pestis ◽  
Drug Target ◽  
Deletion Mutant ◽  
Ex Vivo ◽  
Ion Homeostasis ◽  
Content Type ◽  
Double Deletion ◽  
Derivative Strain

ABSTRACTNa+/H+antiporters are ubiquitous membrane proteins that play a central role in the ion homeostasis of cells. In this study, we examined the possible role of Na+/H+antiport inYersinia pestisvirulence and found thatY. pestisstrains lacking the major Na+/H+antiporters, NhaA and NhaB, are completely attenuated in anin vivomodel of plague. TheY. pestisderivative strain lacking thenhaAandnhaBgenes showed markedly decreased survival in blood and blood serumex vivo. Complementation of eithernhaAornhaBintransrestored the survival of theY. pestis nhaA nhaBdouble deletion mutant in blood. ThenhaA nhaBdouble deletion mutant also showed inhibited growth in an artificial serum medium, Opti-MEM, and a rich LB-based medium with Na+levels and pH values similar to those for blood. Taken together, these data strongly suggest that intact Na+/H+antiport is indispensable for the survival ofY. pestisin the bloodstreams of infected animals and thus might be regarded as a promising noncanonical drug target for infections caused byY. pestisand possibly for those caused by other blood-borne bacterial pathogens.

scholarly journals Hwp1 and Related Adhesins Contribute to both Mating and Biofilm Formation in Candida albicans

2009 ◽  
Vol 8 (12) ◽  
pp. 1909-1913 ◽  
Author(s):  
Iuliana V. Ene ◽  
Richard J. Bennett
Keyword(s):  
Cell Wall ◽  
Candida Albicans ◽  
Sexual Differentiation ◽  
Biofilm Formation ◽  
Filamentous Growth ◽  
Cell Wall Proteins ◽  
Related Cell

ABSTRACT Candida albicans Hwp1, Hwp2, and Rbt1 are related cell wall proteins expressed during the programs of sexual differentiation and filamentous growth. In this study, we compare strains lacking either single factors or a combination of these genes, and we demonstrate distinct but overlapping roles in mating and biofilm formation.

scholarly journals Inactivation of the pgmA Gene in Streptococcus mutans Significantly Decreases Biofilm-Associated Antimicrobial Tolerance

2019 ◽  
Vol 7 (9) ◽  
pp. 310 ◽  
Author(s):  
Martin Nilsson ◽  
Michael Givskov ◽  
Svante Twetman ◽  
Tim Tolker-Nielsen
Keyword(s):  
Cell Wall ◽  
Streptococcus Mutans ◽  
Congo Red ◽  
Biofilm Formation ◽  
Cell Wall Composition ◽  
Mutant Library ◽  
Wild Type ◽  
Glass Slides ◽  
Increased Sensitivity ◽  
Wall Components

Screening of a Streptococcus mutans mutant library indicated that pgmA mutants displayed a reduced biofilm-associated tolerance toward gentamicin. The biofilms formed by the S. mutans pgmA mutant also displayed decreased tolerance towards linezolid and vancomycin compared to wild-type biofilms. On the contrary, the resistance of planktonic S. mutans pgmA cells to gentamycin, linezolid, and vancomycin was more similar to wild-type levels. Investigations of biofilms grown in microtiter trays and on submerged glass slides showed that pgmA mutants formed roughly the same amount of biofilm as the wild type, indicating that the reduced antimicrobial tolerance of these mutants is not due to diminished biofilm formation. The pgmA gene product is known to be involved in the synthesis of precursors for cell wall components such as teichoic acids and membrane glycolipids. Accordingly, the S. mutans pgmA mutant showed increased sensitivity to Congo Red, indicating that it has impaired cell wall integrity. A changed cell wall composition of the S. mutans pgmA mutant may play a role in the increased sensitivity of S. mutans pgmA biofilms toward antibiotics.

scholarly journals Disruption of L-Rhamnose Biosynthesis Results in Severe Growth Defects in Streptococcus mutans

2019 ◽  
Vol 202 (6) ◽  
Author(s):  
Andrew P. Bischer ◽  
Christopher J. Kovacs ◽  
Roberta C. Faustoferri ◽  
Robert G. Quivey
Keyword(s):  
Cell Wall ◽  
Dental Caries ◽  
Oral Cavity ◽  
Streptococcus Mutans ◽  
Biofilm Formation ◽  
Etiologic Agent ◽  
Growth Defect ◽  
Cell Wall Polysaccharide ◽  
Content Type ◽  
Severe Growth

ABSTRACT The rhamnose-glucose cell wall polysaccharide (RGP) of Streptococcus mutans plays a significant role in cell division, virulence, and stress protection. Prior studies examined function of the RGP using strains carrying deletions in the machinery involved in RGP assembly. In this study, we explored loss of the substrate for RGP, l-rhamnose, via deletion of rmlD (encoding the protein responsible for the terminal step in l-rhamnose biosynthesis). We demonstrate that loss of rhamnose biosynthesis causes a phenotype similar to strains with disrupted RGP assembly (ΔrgpG and ΔrgpF strains). Deletion of rmlD not only caused a severe growth defect under nonstress growth conditions but also elevated susceptibility of the strain to acid and oxidative stress, common conditions found in the oral cavity. A genetic complement of the ΔrmlD strain completely restored wild-type levels of growth, whereas addition of exogenous rhamnose did not. The loss of rhamnose production also significantly disrupted biofilm formation, an important aspect of S. mutans growth in the oral cavity. Further, we demonstrate that loss of either rmlD or rgpG results in ablation of rhamnose content in the S. mutans cell wall. Taken together, these results highlight the importance of rhamnose production in both the fitness and the ability of S. mutans to overcome environmental stresses. IMPORTANCE Streptococcus mutans is a pathogenic bacterium that is the primary etiologic agent of dental caries, a disease that affects billions yearly. Rhamnose biosynthesis is conserved not only in streptococcal species but in other Gram-positive, as well as Gram-negative, organisms. This study highlights the importance of rhamnose biosynthesis in RGP production for protection of the organism against acid and oxidative stresses, the two major stressors that the organism encounters in the oral cavity. Loss of RGP also severely impacts biofilm formation, the first step in the onset of dental caries. The high conservation of the rhamnose synthesis enzymes, as well as their importance in S. mutans and other organisms, makes them favorable antibiotic targets for the treatment of disease.

scholarly journals Involvement of Sortase Anchoring of Cell Wall Proteins in Biofilm Formation by Streptococcusmutans

2005 ◽  
Vol 73 (6) ◽  
pp. 3773-3777 ◽  
Author(s):  
Céline M. Lévesque ◽  
Elena Voronejskaia ◽  
Yi-Chen Cathy Huang ◽  
Richard W. Mair ◽  
Richard P. Ellen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Biofilm Formation ◽  
Cell Wall Proteins ◽  
Planktonic Cells ◽  
Genes Encoding

ABSTRACT Streptococcus mutans is one of the best-known biofilm-forming organisms associated with humans. We investigated the role of the sortase gene (srtA) in monospecies biofilm formation and observed that inactivation of srtA caused a decrease in biofilm formation. Genes encoding three putative sortase-dependent proteins were also found to be up-regulated in biofilms versus planktonic cells and mutations in these genes resulted in reduced biofilm biomass.

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