MtaR and methionine influence the expression of Streptococcus agalactiae metQ1 gene.

摘要

Streptococcus agalactiae (group B streptococcus , GBS) is a fastidious Gram-positive pathogen of infants and some adult populations. In these populations GBS can cause severe disease. Much of the pathogenesis caused by GBS infection is reflected by the migratory path GBS takes within the host. To survive in the dynamic environments within the human host, GBS has to be able to tightly regulate gene expression to avoid immune system detection, survive, and grow. The carefully regulated gene expression is thought to be mediated by the numerous transcriptional regulatory proteins encoded by the GBS genome. Our studies sought to further characterize two GBS transcriptional regulatory proteins, LytR and MtaR. LytR is a putative response regulator predicted to function in tandem with a sensor kinase to regulate cell wall hydrolysis. We show that a DeltalytR mutant exhibits wild type growth under routine culture conditions. MtaR is a transcriptional regulator of GBS genes predicted to encode virulence factors and nutrient acquisition genes. We show that a subset of MtaR-regulated genes are responsive to methionine. We also show that mtaR is required for GBS wild type growth in human cerebrospinal and amniotic fluid.