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J. Bacteriol. doi:10.1128/JB.01429-08
Copyright (c) 2008, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Bacillus subtilis late competence operon comE is transcriptionally regulated by yutB and under post-transcription initiation control by comN (yrzD)

Institute of Oceanic Research and Development, Tokai University, 3-20-1 Orido-Shimizu, Shizuoka 424-8610, Japan

^* To whom correspondence should be addressed. Email: oguram{at}scc.u-tokai.ac.jp.

	Abstract

The B. subtilis genome has been sequenced, and disruptants of the genes that were not yet characterized were systematically generated. We screened these gene disruptants for decreased transformation frequency and identified two genes, yrzD and yutB, whose disruption resulted in severely and modestly reduced transformation frequency, respectively. In regulation of competence development, various signals converge to affect the expression of comK, which encodes a master regulator for genetic competence that drives late competence gene transcription. Epistatic analyses of both genes revealed no significant differences in the expression of comK. Further analysis of the expression of late competence genes in the yrzD disruptant revealed that yrzD is specifically required for the regulation of the comE operon, which is one of the late competence operons, and thus renamed comN. An analysis of various comE-lacZ fusions revealed that the target cis-element for the comN action is within the large (approximately 1 Kb) 5'-untranslated region (UTR) of comE, while the activity of the comE promoter was not affected by disruption of comN. These results suggested post-transcription initiation control of comE by comN. A sequential deletion analysis of this region revealed the 35-base pairs region required for the comN action. The yutB gene encodes a putative lipoic acid synthetase, and yet is specifically required for the transcription of comE, based on the results of lacZ fusion analyses. Therefore, yutB and comN regulates comE at transcription and post-transcription initiation levels, respectively. These results demonstrate a comE-specific regulatory mechanism in genetic competence development.