HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Gaballa, A. Articles by Helmann, J. D. Search for Related Content PubMed PubMed Citation Articles by Gaballa, A. Articles by Helmann, J. D. Agricola Articles by Gaballa, A. Articles by Helmann, J. D.

Two MerR homologues that affect copper induction of the Bacillus subtilis copZA operon

Department of Microbiology, Wing Hall, Cornell University, Ithaca, NY 14853-8101, USA

Correspondence
John D. Helmann
jdh9{at}cornell.edu

Copper ions induce expression of the Bacillus subtilis copZA operon encoding a metallochaperone, CopZ, and a CPx-type ATPase efflux protein, CopA. The copZA promoter region contains an inverted repeat sequence similar to that recognized by the mercury-sensing MerR protein. To investigate the possible involvement of MerR homologues in copZA regulation, null mutations were engineered affecting each of four putative MerR-type regulators: yyaN, yraB, yfmP and yhdQ. Two of these genes affected copper regulation. Mutation of yhdQ (hereafter renamed cueR) dramatically reduced copper induction of copZA, and purified CueR bound with high affinity to the copZA promoter region. These results suggest that CueR is a direct regulator of copZA transcription that mediates copper induction. Surprisingly, a yfmP mutation also reduced copper induction of copZA. Sequence analysis suggested that yfmP was cotranscribed with yfmO, encoding a putative multidrug efflux protein. The yfmPO operon is autoregulated: a yfmP mutation derepressed the yfmP promoter and purified YfmP bound the yfmP promoter region, but not the copZA promoter region. Since the yfmP mutant strain was predicted to express elevated levels of the YfmO efflux pump, it was hypothesized that copper efflux might be responsible for the reduced copZA induction. Consistent with this model, in a yfmP yfmO double mutant copper induction of copZA was normal. The results demonstrate the direct regulation of the B. subtilis copper efflux system by CueR, and indirect regulation by a putative multidrug efflux system.

This article has been cited by other articles:

				G. T. Smaldone and J. D. Helmann CsoR regulates the copper efflux operon copZA in Bacillus subtilis Microbiology, December 1, 2007; 153(12): 4123 - 4128. [Abstract] [Full Text] [PDF]