Mycobacterium smegmatis L-alanine dehydrogenase (Ald) is required for proficient utilization of alanine as a sole nitrogen source and sustained anaerobic growth.

ABSTRACT: NAD(H)-dependent L-alanine dehydrogenase (EC 1.4.1.1) (Ald) catalyzes the oxidative deamination of L-alanine and the reductive amination of pyruvate. To assess the physiological role of Ald in Mycobacterium smegmatis, we cloned the ald gene, identified its promoter, determined the protein expression levels, and analyzed the combined effects of nutrient supplementation, oxygen availability, and growth stage on enzyme activity. High Ald activities were observed in cells grown in the presence of L- or D-alanine regardless of the oxygen availability and growth stage. In exponentially growing cells under aerobic conditions, supplementation with alanine resulted in a 25- to 50-fold increase in the enzyme activity. In the absence of alanine supplementation, 23-fold-higher Ald activities were obse

SUBMITTER: Feng Z 

PROVIDER: S-EPMC135311 | biostudies-literature | 2002 Sep

REPOSITORIES: biostudies-literature