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AmiA is a negative regulator of acetamidase expression in Mycobacterium smegmatis.

ABSTRACT: BACKGROUND:The acetamidase of Mycobacterium smegmatis is a highly inducible enzyme. Expression of this enzyme is increased 100-fold when the substrate acetamide is present. The acetamidase gene is found immediately downstream of three open reading frames. Two of these are proposed to be involved in regulation. RESULTS:We constructed a deletion mutant in one of the upstream ORFs (amiA). This mutant (Mad1) showed a constitutively high level of acetamidase expression. We identified four promoters in the upstream region using a beta-galactosidase reporter gene. One of these (P2) was inducible in the wild-type, but was constitutively active in Mad1. CONCLUSIONS:These results demonstrate that amiA encodes a negative regulatory protein which interacts with P2. Since amiA has homology to DNA-binding proteins, it is likely that it exerts the regulatory effect by binding to the promoter to prevent transcription.

SUBMITTER: Parish T

PROVIDER: S-EPMC56589 | biostudies-literature | 2001

REPOSITORIES: biostudies-literature

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amiA is a negative regulator of acetamidase expression in Mycobacterium smegmatis.

Parish T T Turner J J Stoker N G NG

BMC microbiology 20010831

<h4>Background</h4>The acetamidase of Mycobacterium smegmatis is a highly inducible enzyme. Expression of this enzyme is increased 100-fold when the substrate acetamide is present. The acetamidase gene is found immediately downstream of three open reading frames. Two of these are proposed to be involved in regulation.<h4>Results</h4>We constructed a deletion mutant in one of the upstream ORFs (amiA). This mutant (Mad1) showed a constitutively high level of acetamidase expression. We identified f ...[more]

PMID: 11570974

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