Abstract
Our previous studies suggested that the essential two-component signal transduction system, YhcSR, regulates the opuCABCD operon at the transcriptional level, and the Pspac-driven opuCABCD partially complements the lethal effects of yhcS antisense RNA expression in Staphylococcus aureus. However, the reason why yhcSR regulon is required for growth is still unclear. In this report, we present that the lac and opuC operons are directly transcriptionally regulated by YhcSR. Using real-time RT-PCR we showed that the down-regulation of yhcSR expression affected the transcription of lacA encoding galactose-6-phosphotase isomerase subunit LacA, and opuCA encoding a subunit of a glycine betaine/carnitine/choline ABC transporter. Promoter-lux reporter fusion studies further confirmed the transcriptional regulation of lac by YhcSR. Gel shift assays revealed that YhcR binds to the promoter regions of the lac and opuC operons. Moreover, the Pspac-driven lacABC expression in trans was able to partially complement the lethal effect of induced yhcS antisense RNA. Likewise, the Pspac-driven opuCABCD expression in trans complemented the growth defect of S. aureus in a high osmotic strength medium during the depletion of YhcSR. Taken together, the above data indicate that the yhcSR system directly regulates the expression of lac and opuC operons, which, in turn, may be partially associated with the essentiality of yhcSR in S. aureus. These results provide a new insight into the biological functions of the yhcSR, a global regulator.
Highlights
The continuing increase of hospital- and community-associated methicillin resistant Staphylococcus aureus infections highlights an urgent need for the development of alternative potent antibacterial agents [1,2,3]
Using a Pspac-regulated yhcSR mutant and a TetR-regulated yhcS antisense RNA mutant, we have demonstrated that the downregulation of yhcSR expression causes a lethal effect on bacterial growth [10]
In order to elucidate the biological functions of the essential yhcSR system in S. aureus, we comprehensively examined the effect of conditional knockdown of yhcSR on gene expression using regulated antisense RNA technology with the combination of microarray analysis
Summary
The continuing increase of hospital- and community-associated methicillin resistant Staphylococcus aureus infections highlights an urgent need for the development of alternative potent antibacterial agents [1,2,3] The ability of this organism to resist current antibiotic therapies and cause infection is partially due to the coordinated regulation of gene expression allowing the bacteria to survive in different stress conditions. Two-component signal (TCS) transduction systems are important sensory units and allow microbial organisms to adapt to different niches, as well as play a significant role in pathogenesis and biofilm formation for various bacterial species [4,5,6,7] Interrupting these critical signaling pathways may provide an alternative strategy for the development of novel classes of preventive and/or therapeutic antibacterial agents [8]. The yycFG system, which has orthologs in Bacillus subtilis [12] and Streptococcus pneumoniae [13], is the first reported
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