Unknown,Transcriptomics,Genomics,Proteomics

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SarZ is a key regulator of biofilm formation and virulence in Staphylococcus epidermidis

ABSTRACT: Biofilm-associated infection by the leading nosocomial pathogen Staphylococcus epidermidis is a major problem for the public health system. Here we used an especially discriminatory, two-step screen to discover key biofilm factors. We identified the transcriptional regulator and SarA paralog SarZ as a novel important determinant of biofilm formation and biofilm-associated infection by S. epidermidis. Notably, a sarZ mutant strain exhibited significantly reduced survival in two different models of biofilm-associated infection. Further, in addition to its significant influence on the transcription of the biosynthetic operon for S. epidermidis biofilm exopolysaccharide, sarZ impacted the expression of a series of virulence factors, including lipases and proteases. As a likely consequence of the regulated proteolytic activity, we observed increased resistance to an important human antimicrobial peptide, indicating a role for sarZ in the regulation of immune evasion. Interestingly, sarZ deficiency led to a hemolytic phenotype, a feature not commonly observed in S. epidermidis. Thus, our study indicates a key role for the SarZ regulator in maintaining the typical S. epidermidis phenotype, which is characterized by pronounced biofilm formation, immune evasion, and suppressed acute virulence, a likely reason for the success of S. epidermidis as a colonizer and pathogen in chronic, biofilm-associated infection. Keywords: Wild type control vs mutant Wild type untreated in triplicate is compared to SarZ mutant in triplicate

ORGANISM(S): Staphylococcus epidermidis

SUBMITTER: Daniel Sturdevant

PROVIDER: E-GEOD-8523 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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SarZ is a key regulator of biofilm formation and virulence in Staphylococcus epidermidis.

Wang Li L Li Min M Dong Dandan D Bach Thanh-Huy L TH Sturdevant Daniel E DE Vuong Cuong C Otto Michael M Gao Qian Q

The Journal of infectious diseases 20080501 9

Biofilm-associated infection due to Staphylococcus epidermidis, the leading nosocomial pathogen, is a major problem for the public health system, but the regulation of this important phenotype is not completely understood. Using a highly discriminatory screening procedure for genes that influence biofilm formation, we identified the transcriptional regulator SarZ as a novel important determinant of biofilm formation and biofilm-associated infection, on the basis of the significant impact of sarZ ...[more]

PMID: 18422437

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Project description:The staphylococcal accessory regulator A (sarA) impacts the extracellular accumulation of Staphylococcus aureus virulence factors at the level of intracellular production and extracellular protease-mediated degradation. To assess the relative impact of these two functions, we previously used a proteomics approach that measures protein abundance as a function of all proteoforms to demonstrate that mutation of sarA results in increased levels of extracellular proteases and assess the impact of this on the accumulation of S. aureus exoproteins1. While this approach confirmed that protease-mediated degradation has a significant impact on the S. aureus exoproteome, it was potentially limited in that it did not take into account the possibility that large, stable proteolytic products from a given protein could result in false negatives when quantified by total proteoforms. Here, we present an expanded proteomics approach that utilizes a dual quantitative method for measuring abundance at both the total proteoform and full-length exoprotein levels. Specifically, proteins present in conditioned medium from overnight, stationary phase cultures of the USA300 strain LAC, an isogenic sarA mutant, and a sarA mutant unable to produce any of the known extracellular proteases (sarA/protease) were resolved using one-dimensional gel electrophoresis. Using methods that focus on total proteoforms vs. methods that focus specifically on full-length proteins, quantitative proteomic comparisons of sarA vs sarA/protease mutants identified proteins that were degraded in a protease dependent manner owing to mutation of sarA, while comparisons of a sarA/protease mutant vs the LAC parent strain identified proteins in which abundance was altered in a sarA mutant in a protease-independent manner. Furthermore, the proteins uniquely identified by the full-length data analysis approach eliminated false negatives observed in the total proteoform analysis. This approach provided for a more comprehensive and robust analysis of the impact of mutating sarA and protease-mediated degradation on the S. aureus exoproteome.

Project description:Biofilm formation is considered the most important factor involved in pathogenicity of Staphylococcus epidermidis.We investigated the role of two-component signal transduction system (TCS) srrAB, which was up-regulated under micro-aerobic condition, in the growth and biofilm formation of S. epidermidis.AsrrA-deficient mutant (M-bM-^HM-^FsrrA) derived from S. epidermidis1457 (SE1457), exhibited dramatic reduction in growth and biofilm formation underboth aerobic and micro-aerobic conditions, and more sensitive to several different types of antimicrobial agents, H2O2 and SDS. In New Zealand Rabbit model of S. epidermidis biofilm infection, M-bM-^HM-^FsrrA hardly formed biofilm compared to that of SE1457. Phenotypic alteration was restored to the wide-type levelwhen srrAB were complemented into M-bM-^HM-^FsrrA. Further study found that the initial adherence capacity and production of polysaccharide intercellular adhesion (PIA) in M-bM-^HM-^FsrrA were decreased, while extracellular DNA (eDNA) was increased. Transcriptional Analysisby qRT-PCR demonstrated that expression level of icaRin M-bM-^HM-^FsrrA was up-regulated compared to that of SE1457 under aerobic condition, while down-regulated under micro-aerobic condition;icaA and altE were down-regulated under both conditions. Expression of genes involved in respiratory metabolism, such as qoxB(quinol oxidase polypeptide II), ctaA(heme A synthase), and pfl(pyruvate formatelyase), etc. were down-regulated in M-bM-^HM-^FsrrAunder both conditions. Electrophoretic mobility shift assay (EMSA) revealed that phosphorylated SrrA bound to the promoter regions of icaR, icaA, atlE, qoxB,ctaA, andpflB just like binding its own promoter region srr. Taken together, our results demonstrate that srrAB may provide a mechanistic link between respiratory metabolism, environmental signals, and regulation of biofilm formation in S. epidermidis. Microarrays covering different S. epidermidis genomes were used to assess the impact of the two component system srrAB on growth and biofilm formation, by comparing WT with srrA mutant transcriptomes

Dataset Information

SarZ is a key regulator of biofilm formation and virulence in Staphylococcus epidermidis

Publications

SarZ is a key regulator of biofilm formation and virulence in Staphylococcus epidermidis.

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