Journal Article

Molybdate-dependent transcription of <i>hyc</i> and <i>nar</i> operons of <i>Escherichia coli</i> requires MoeA protein and ModE-molybdate

Adnan Hasona, William T Self, Ramesh M Ray and K.T Shanmugam

in FEMS Microbiology Letters

Volume 169, issue 1, pages 111-116
Published in print December 1998 |
Published online January 2006 | e-ISSN: 1574-6968 | DOI:

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In Escherichia coli, ModE-molybdate, a repressor of modABCD operon (molybdate transport), was previously shown to be an additional transcriptional activator of hyc operon (formate hydrogenlyase) and narGHJI operon (respiratory nitrate reductase). However, in a modE mutant, both operons were expressed at about 50% of the wild-type level in a molybdate-dependent manner. This ModE-independent, molybdate-dependent, expression of hyc, narG and narK operons required MoeA protein. An E. coli modE, moeA double mutant failed to produce formate hydrogenlyase or respiratory nitrate reductase activity irrespective of the growth medium. Tungstate substituted for molybdate in the activation of transcription of hyc and nar operons by ModE could not replace molybdate for MoeA-dependent expression. It is proposed that the MoeA-catalyzed product, an activated form of molybdate, interacts with a transcriptional activator/regulator other than ModE and regulates hyc and nar operons.

Keywords: Molybdate; Regulation; ModE; MoeA; Formate hydrogenlyase; nar operon; Escherichia coli

Journal Article.  2592 words. 

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