| Research Abstract |
As part of the comprehensive function analysis of the HTH-regulatory proteins in the framework of Bacillus subtilis post-genome project, we conducted the function analysis of the regulons governed by the MarR, MerR and TetR families of the HTH-regulatory proteins, the targets of which tend to be drug-resistance genes. Out of them, we list those which are the prominent achievements from their analysis. (i) The YsiA regulon was found to be involved in fatty acid β-oxidation, whose members are five operons (ysiAB-etfBA, ykuFG, yhfL, yusLKJ, and ywjF-acdA-rpoE). Each of these operons carry a YsiA-box in its promoter region to which YsiA binds. The in vivo and in vitro analyses revealed that long chain fatty acyl-CoAs with 14 to 20 carbon atoms antagonized the YsiA protein. (ii) The LmrA/YxaF regulon comprises lmrAB, yxaGH, and yxaF was found to be involved in flavonoid degradation as well as lincomycin resistance, which were dually regulated by the LmrA and YxaF proteins. It was considered that lincomycin resistance is not induced by lincomycin, but the lmrB gene responsible to lincomycin exhaust is likely related to flavonoid degradation by chance. (iii) The YkvE regulon comprising ykcABC, ydfNOP, yodED, and yvaB is likely induced by chlorohydroquinone. (iv) The yhblJ-yhcAB operon was induced by indole acetic acid, which is repressed by YhbI. This operon is likely involved in indole acetic acid secretion. (v) The analysis of multi-drug resistant operons revealed that YcnC, YusO, and YwoH negatively regulate ycnCB, yusOP, and ywoHG, respectively.
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