<it>amiA</it> is a negative regulator of acetamidase expression in <it>Mycobacterium smegmatis</it>

• Main Authors: Turner Jane, Parish Tanya, Stoker Neil G
• Format: Article
• Language: English
• Published: BMC 2001-08-01
• Series: BMC Microbiology
• Online Access: http://www.biomedcentral.com/1471-2180/1/19
• ISSN: 1471-2180

<p>Abstract</p> <p>Background</p> <p>The acetamidase of <it>Mycobacterium smegmatis</it> 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.</p> <p>Results</p> <p>We constructed a deletion mutant in one of the upstream ORFs (<it>amiA</it>). This mutant (Mad1) showed a constitutively high level of acetamidase expression. We identified four promoters in the upstream region using a β-galactosidase reporter gene. One of these (P₂) was inducible in the wild-type, but was constitutively active in Mad1.</p> <p>Conclusions</p> <p>These results demonstrate that <it>amiA</it> encodes a negative regulatory protein which interacts with P₂. Since <it>amiA</it> has homology to DNA-binding proteins, it is likely that it exerts the regulatory effect by binding to the promoter to prevent transcription.</p>