Regulation of the intercellular adhesin (ica) locus under anaerobic conditions in Staphylococcus aureus

金黄色葡萄球菌和表皮葡萄球菌的细胞间粘附（ica）操纵子的产物合成线性的<s:1> -1,6连接的氨基葡萄糖多糖。这种细胞外多糖介导细菌粘附和生物膜的形成，这被认为增加了与假体生物医学植入物相关的两种病原体的毒力。我们证明了体外厌氧生长导致两种细菌的多糖表达增加。厌氧也显著刺激ica-和多糖阳性菌株中ica特异性mRNA的表达。这些数据提示了ica基因表达和多糖产生可能在体内厌氧环境中作为毒力因子的机制。本项目旨在识别和表征在厌氧条件下调节ica表达的因子。染色体ica启动子- <e:1> -半乳糖苷酶报告系统将用于厌氧和有氧条件下ica转录的遗传筛选。还将研究先前确定的两个因素（SigB和SsrA/B）对厌氧条件下ica活性的影响。最后，当金黄色葡萄球菌微阵列芯片在本研究过程中可用时，我们将使用好氧和厌氧条件下的RNA表达模式来表征调节因子及其靶标。

Products of the intercellular adhesion (ica) operon in Staphylococcus aureus and S. epidermidis synthesize a linear â-1,6 linked glucosaminglycan. This extracellular polysaccharide mediates bacterial adhesion and biofilm formation, which is thought to increase the virulence of both pathogens in association with prosthetic biomedical implants. We demonstrated that anaerobic growth in vitro leads to increased polysaccharide expression in both bacteria. Anaerobiosis also dramatically stimulates ica-specific mRNA expression in ica- and polysaccharide-positive strains. These data suggest a mechanism whereby ica gene expression and polysaccharide production may act as a virulence factor in an anaebobic environment in vivo. This project aims to identify and characterize the factor(s) that regulate ica expression in response to anaerobic conditions. A chromosomal ica-promotor-â-galactosidase reporter system will be used in a genetic screen for ica transcription under anaerobic and aerobic conditions. The influence of two previously identified factors (SigB and SsrA/B) on ica activity under anaerobic conditions will also be investigated. Finally, when a S. aureus micro-array chip becomes available during the course of this study, we will use RNA expression patterns under aerobic and anaerobic conditions to characterize regulator(s) and their target(s).