Co 2+-dependent gene expression in Streptococcus pneumoniae: opposite effect of Mn 2+ and Co 2+ on the expression of the virulence genes psaBCA, pcpA, and prtA

摘要

Manganese (Mn~(2+))-, zinc (Zn~(2+))- and copper (Cu~(2+)) play significant roles in transcriptional gene regulation, physiology, and virulence of Streptococcus pneumoniae . So far, the effect of the important transition metal ion cobalt (Co~(2+)) on gene expression of S. pneumoniae has not yet been explored. Here, we study the impact of Co~(2+)stress on the transcriptome of S. pneumoniae strain D39. BLAST searches revealed that the genome of S. pneumoniae encodes a putative Co~(2+)-transport operon ( cbi operon), the expression of which we show here to be induced by a high Co~(2+)concentration. Furthermore, we found that Co~(2+), as has been shown previously for Zn~(2+), can cause derepression of the genes of the PsaR virulence regulon, encoding the Mn~(2+)-uptake system PsaBCA, the choline binding protein PcpA and the cell-wall associated serine protease PrtA. Interestingly, although Mn~(2+)represses expression of the PsaR regulon and Co~(2+)leads to derepression, both metal ions stimulate interaction of PsaR with its target promoters. These data will be discussed in the light of previous studies on similar metal-responsive transcriptional regulators.