OxyR-controlled surface polysaccharide production and biofilm formation in Acinetobacter oleivorans DR1

2019 ◽  
Vol 104 (3) ◽  
pp. 1259-1271 ◽  
Author(s):  
Bora Shin ◽  
Chulwoo Park ◽  
Woojun Park
Keyword(s):  
Biofilm Formation ◽  
Polysaccharide Production ◽  
Surface Polysaccharide

scholarly journals The Transcriptional Regulator BpsR Controls the Growth ofBordetella bronchisepticaby Repressing Genes Involved in Nicotinic Acid Degradation

2018 ◽  
Vol 200 (12) ◽  
pp. e00712-17 ◽  
Author(s):  
Manita Guragain ◽  
Jamie Jennings-Gee ◽  
Natalia Cattelan ◽  
Mary Finger ◽  
Matt S. Conover ◽  
...  
Keyword(s):  
Nicotinic Acid ◽  
Biofilm Formation ◽  
Transcriptional Control ◽  
Bordetella Bronchiseptica ◽  
Negative Regulator ◽  
Growth Defect ◽  
Content Type ◽  
Polysaccharide Production ◽  
Expression Of Genes

ABSTRACTMany of the pathogenic species of the genusBordetellahave an absolute requirement for nicotinic acid (NA) for laboratory growth. These Gram-negative bacteria also harbor a gene cluster homologous to theniccluster ofPseudomonas putidawhich is involved in the aerobic degradation of NA and its transcriptional control. We report here that BpsR, a negative regulator of biofilm formation and Bps polysaccharide production, controls the growth ofBordetella bronchisepticaby repressing the expression ofnicgenes. The severe growth defect of the ΔbpsRstrain in Stainer-Scholte medium was restored by supplementation with NA, which also functioned as an inducer ofnicgenes at low micromolar concentrations that are usually present in animals and humans. Purified BpsR protein bound to thenicpromoter region, and its DNA binding activity was inhibited by 6-hydroxynicotinic acid (6-HNA), the first metabolite of the NA degradative pathway. Reporter assays with the isogenic mutant derivative of the wild-type (WT) strain harboring deletion innicA, which encodes a putative nicotinic acid hydroxylase responsible for conversion of NA to 6-HNA, showed that 6-HNA is the actual inducer of thenicgenes in the bacterial cell. Gene expression profiling further showed that BpsR dually activated and repressed the expression of genes associated with pathogenesis, transcriptional regulation, metabolism, and other cellular processes. We discuss the implications of these findings with respect to the selection of pyridines such as NA and quinolinic acid for optimum bacterial growth depending on the ecological niche.IMPORTANCEBpsR, the previously described regulator of biofilm formation and Bps polysaccharide production, controlsBordetella bronchisepticagrowth by regulating the expression of genes involved in the degradation of nicotinic acid (NA). 6-Hydroxynicotinic acid (6-HNA), the first metabolite of the NA degradation pathway prevented BpsR from binding to DNA and was the actualin vivoinducer. We hypothesize that BpsR enablesBordetellabacteria to efficiently and selectively utilize NA for their survival depending on the environment in which they reside. The results reported herein lay the foundation for future investigations of how BpsR and the alteration of its activity by NA orchestrate the control ofBordetellagrowth, metabolism, biofilm formation, and pathogenesis.

scholarly journals A Quorum-Sensing System That Regulates Streptococcus pneumoniae Biofilm Formation and Surface Polysaccharide Production

mSphere ◽  
2017 ◽  
Vol 2 (5) ◽  
Author(s):  
Roger Junges ◽  
Gabriela Salvadori ◽  
Sudhanshu Shekhar ◽  
Heidi A. Åmdal ◽  
Jimstan N. Periselneris ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Gene Cluster ◽  
Biofilm Formation ◽  
Parent Strain ◽  
Single Gene ◽  
Content Type ◽  
Sensing System ◽  
Quorum Sensing System ◽  
Surface Polysaccharide ◽  
Capsule Size

ABSTRACT Quorum sensing regulates bacterial social behaviors by production, secretion, and sensing of pheromones. In this study, we characterized a new quorum-sensing system of the Rgg/SHP class in S. pneumoniae D39. The system was found to directly induce the expression of a single gene cluster comprising the gene for the SHP pheromone and genes with putative functions in capsule synthesis. Capsule size, as measured by dextran exclusion, was increased by SHP exposure in R36A, an unencapsulated derivative of D39. In the encapsulated parent strain, overexpression of the gene cluster increased capsule size, supporting the role of Rgg/SHP in the synthesis of surface polysaccharides. Further, we found that biofilm formation on epithelial cells was reduced by overexpression of the system and increased in a mutant with an rgg deletion. Placing surface polysaccharide expression under quorum-sensing regulation may enable S. pneumoniae to tune interactions with the host and other bacteria in accordance with environmental and cell density conditions. Despite vaccines, Streptococcus pneumoniae kills more than a million people yearly. Thus, understanding how pneumococci transition from commensals to pathogens is particularly relevant. Quorum sensing regulates collective behaviors and thus represents a potential driver of commensal-to-pathogen transitions. Rgg/small hydrophobic peptide (SHP) quorum-sensing systems are widespread in streptococci, yet they remain largely uncharacterized in S. pneumoniae. Using directional transcriptome sequencing, we show that the S. pneumoniae D39 Rgg0939/SHP system induces the transcription of a single gene cluster including shp and capsule gene homologs. Capsule size measurements determined by fluorescein isothiocyanate-dextran exclusion allowed assignment of the system to the regulation of surface polysaccharide expression. We found that the SHP pheromone induced exopolysaccharide expression in R36A, an unencapsulated derivative of D39. In the encapsulated parent strain, overexpression of the Rgg system resulted in a mutant with increased capsule size. In line with previous studies showing that capsule expression is inversely associated with biofilm formation, we found that biofilm formed on lung epithelial cells was decreased in the overexpression strain and increased in an rgg deletion mutant. Although no significant differences were observed between D39 and the rgg deletion mutant in a mouse model of lung infection, in competitive assays, overexpression reduced fitness. This is the first study to reveal a quorum-sensing system in streptococci that regulates exopolysaccharide synthesis from a site distinct from the original capsule locus. IMPORTANCE Quorum sensing regulates bacterial social behaviors by production, secretion, and sensing of pheromones. In this study, we characterized a new quorum-sensing system of the Rgg/SHP class in S. pneumoniae D39. The system was found to directly induce the expression of a single gene cluster comprising the gene for the SHP pheromone and genes with putative functions in capsule synthesis. Capsule size, as measured by dextran exclusion, was increased by SHP exposure in R36A, an unencapsulated derivative of D39. In the encapsulated parent strain, overexpression of the gene cluster increased capsule size, supporting the role of Rgg/SHP in the synthesis of surface polysaccharides. Further, we found that biofilm formation on epithelial cells was reduced by overexpression of the system and increased in a mutant with an rgg deletion. Placing surface polysaccharide expression under quorum-sensing regulation may enable S. pneumoniae to tune interactions with the host and other bacteria in accordance with environmental and cell density conditions.

scholarly journals Regulator RcsB Controls Prodigiosin Synthesis and Various Cellular Processes in Serratia marcescens JNB5-1

2020 ◽  
Vol 87 (2) ◽  
Author(s):  
Xuewei Pan ◽  
Mi Tang ◽  
Jiajia You ◽  
Fei Liu ◽  
Changhao Sun ◽  
...  
Keyword(s):  
Cell Motility ◽  
Serratia Marcescens ◽  
Biofilm Formation ◽  
Capsular Polysaccharide ◽  
Regulatory Mechanism ◽  
Acid Resistance ◽  
Content Type ◽  
Cellular Processes ◽  
Polysaccharide Production ◽  
Insight Into

ABSTRACT Prodigiosin (PG), a red linear tripyrrole pigment normally secreted by Serratia marcescens, has received attention for its reported immunosuppressive, antimicrobial, and anticancer properties. Although several genes have been shown to be important for prodigiosin synthesis, information on the regulatory mechanisms behind this cellular process remains limited. In this work, we identified that the transcriptional regulator RcsB encoding gene BVG90_13250 (rcsB) negatively controlled prodigiosin biosynthesis in S. marcescens. Disruption of rcsB conferred a remarkably increased production of prodigiosin. This phenotype corresponded to negative control of transcription of the prodigiosin-associated pig operon by RcsB, probably by binding to the promoter region of the prodigiosin synthesis positive regulator FlhDC. Moreover, using transcriptomics and further experiments, we revealed that RcsB also controlled some other important cellular processes, including swimming and swarming motilities, capsular polysaccharide production, biofilm formation, and acid resistance (AR), in S. marcescens. Collectively, this work proposes that RcsB is a prodigiosin synthesis repressor in S. marcescens and provides insight into the regulatory mechanism of RcsB in cell motility, capsular polysaccharide production, and acid resistance in S. marcescens. IMPORTANCE RcsB is a two-component response regulator in the Rcs phosphorelay system, and it plays versatile regulatory functions in Enterobacteriaceae. However, information on the function of the RcsB protein in bacteria, especially in S. marcescens, remains limited. In this work, we illustrated experimentally that the RcsB protein was involved in diverse cellular processes in S. marcescens, including prodigiosin synthesis, cell motility, capsular polysaccharide production, biofilm formation, and acid resistance. Additionally, the regulatory mechanism of the RcsB protein in these cellular processes was investigated. In conclusion, this work indicated that RcsB could be a regulator for prodigiosin synthesis and provides insight into the function of the RcsB protein in S. marcescens.

scholarly journals Molecular Basis for Preferential Protective Efficacy of Antibodies Directed to the Poorly Acetylated Form of Staphylococcal Poly-N-Acetyl-β-(1-6)-Glucosamine

2007 ◽  
Vol 75 (7) ◽  
pp. 3406-3413 ◽  
Author(s):  
Nuno Cerca ◽  
Kimberly K. Jefferson ◽  
Tomas Maira-Litrán ◽  
Danielle B. Pier ◽  
Casie Kelly-Quintos ◽  
...  
Keyword(s):  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Molecular Basis ◽  
Protective Efficacy ◽  
Human Monoclonal Antibody ◽  
Protective Activity ◽  
Survival Capacity ◽  
Vaccine Potential ◽  
Surface Polysaccharide ◽  
Overexpressing Strain

ABSTRACT Poly-N-acetyl-glucosamine (PNAG) is a staphylococcal surface polysaccharide influencing biofilm formation that is also under investigation for its vaccine potential. Antibodies that bind to PNAG with either low (<15%) or high (>90%) levels of acetate are superior at opsonic and protective activity compared with antibodies that bind to PNAG with only high levels (>70%) of acetate. PNAG is synthesized by four proteins encoded within the intercellular adhesin (ica) locus icaADBC. In Staphylococcus epidermidis, icaB encodes a deacetylase needed for the surface retention of PNAG and optimal biofilm formation. In this study, we confirmed that icaB plays a similar role in Staphylococcus aureus and found that an icaB mutant of S. aureus expressed significantly less surface-associated PNAG, was highly susceptible to antibody-independent opsonic killing that could not be enhanced with antibody raised against deacetylated PNAG (dPNAG), and had reduced survival capacity in a murine model of bacteremia. In contrast, an icaB-overexpressing strain produced primarily surface-associated PNAG, was more susceptible to opsonophagocytosis with antibody to dPNAG, and had increased survival in a murine bacteremia model. The highly acetylated secreted PNAG was more effective at blocking opsonic killing mediated by a human monoclonal antibody (mAb) to native PNAG than it was at blocking killing mediated by a human mAb to dPNAG, which by itself was a more effective opsonin. Retention of dPNAG on the surface of S. aureus is key to increased survival during bacteremia and also provides a molecular mechanism explaining the superior opsonic and protective activity of antibody to dPNAG.

scholarly journals Influence of sub-inhibitory concentrations of antimicrobials on micrococcal nuclease and biofilm formation in Staphylococcus aureus

2020 ◽  
Author(s):  
Jelmer Sjollema ◽  
Henny van der Mei ◽  
Colin Rosman
Keyword(s):  
Staphylococcus Aureus ◽  
Biofilm Formation ◽  
Extracellular Polymeric Substances ◽  
Extracellular Dna ◽  
Micrococcal Nuclease ◽  
Major Contributor ◽  
Polysaccharide Production ◽  
Minimum Inhibitory Concentrations ◽  
The Impact

Abstract A major contributor to biomaterial associated infection (BAI) is Staphylococcus aureus. This pathogen produces a protective biofilm, making eradication difficult. Biofilms are composed of bacteria encapsulated in a matrix of extracellular polymeric substances (EPS) comprising polysaccharides, proteins and extracellular DNA (eDNA). S. aureus also produces micrococcal nuclease (MN), an endonuclease which contributes to biofilm composition and dispersion, mainly expressed by nuc1. MN expression can be modulated by sub-minimum inhibitory concentrations of antimicrobials. We investigated the relation between the biofilm and MN expression and the impact of the application of antimicrobial pressure on this relation. Planktonic and biofilm cultures of three S. aureus strains, including a nuc1 deficient strain, were cultured under antimicrobial pressure. Results indicated that nuc1 deletion stimulates the polysaccharide production per CFU in the biofilm in in vitro biofilms. Also antimicrobial pressure of ciproflocacin, doxycycline and erythromycin resulted in significantly increased quantities of polysaccharides per CFU, but this did only coincide with significantly reduced MN activity in erythromycin. Resveratrol significantly reduced MN production per CFU but did not affect polysaccharides production. In conclusion, various antimicrobials impact the balance of eDNA, polysaccharides and MN production, all in a different way.

scholarly journals Differential Roles of Poly-N-Acetylglucosamine Surface Polysaccharide and Extracellular DNA in Staphylococcus aureus and Staphylococcus epidermidis Biofilms

2007 ◽  
Vol 74 (2) ◽  
pp. 470-476 ◽  
Author(s):  
Era A. Izano ◽  
Matthew A. Amarante ◽  
William B. Kher ◽  
Jeffrey B. Kaplan
Keyword(s):  
Staphylococcus Aureus ◽  
Staphylococcus Epidermidis ◽  
Biofilm Formation ◽  
Cetylpyridinium Chloride ◽  
Microtiter Plate ◽  
Dnase I ◽  
Extracellular Dna ◽  
Human Pathogens ◽  
Microtiter Plate Assay ◽  
Surface Polysaccharide

ABSTRACT Staphylococcus aureus and Staphylococcus epidermidis are major human pathogens of increasing importance due to the dissemination of antibiotic-resistant strains. Evidence suggests that the ability to form matrix-encased biofilms contributes to the pathogenesis of S. aureus and S. epidermidis. In this study, we investigated the functions of two staphylococcal biofilm matrix polymers: poly-N-acetylglucosamine surface polysaccharide (PNAG) and extracellular DNA (ecDNA). We measured the ability of a PNAG-degrading enzyme (dispersin B) and DNase I to inhibit biofilm formation, detach preformed biofilms, and sensitize biofilms to killing by the cationic detergent cetylpyridinium chloride (CPC) in a 96-well microtiter plate assay. When added to growth medium, both dispersin B and DNase I inhibited biofilm formation by both S. aureus and S. epidermidis. Dispersin B detached preformed S. epidermidis biofilms but not S. aureus biofilms, whereas DNase I detached S. aureus biofilms but not S. epidermidis biofilms. Similarly, dispersin B sensitized S. epidermidis biofilms to CPC killing, whereas DNase I sensitized S. aureus biofilms to CPC killing. We concluded that PNAG and ecDNA play fundamentally different structural roles in S. aureus and S. epidermidis biofilms.

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