Open AccessAspartate metabolism in Mycobacterium avium grown in host tissue an axenically and in Mycobacterium leprae
Author(s) -
Venkataraman Sritharan,
Paul R. Wheeler,
Colin Ratledge
Publication year - 1990
Publication title -
journal of general microbiology/journal of general microbiology
Language(s) - English
Resource type - Journals
eISSN - 2059-9323
pISSN - 0022-1287
DOI - 10.1099/00221287-136-1-203
Subject(s) - mycobacterium leprae , mycobacterium , microbiology and biotechnology , mycobacterium smegmatis , biology , threonine , methionine , biochemistry , bacteria , serine , enzyme , amino acid , mycobacterium tuberculosis , medicine , tuberculosis , leprosy , genetics , pathology , immunology
Aspartokinase activity was detected in extracts from Mycobacterium leprae (recovered from armadillo liver) and in Mycobacterium avium grown axenically and in vivo. Homoserine dehydrogenase activity was only detected in M. leprae and in M. avium grown axenically. Activities, when detected, were 50 to 70% lower in M. leprae or M. avium grown in vivo than in axenically grown M. avium. In these two pathogenic mycobacteria, aspartokinase and homoserine dehydrogenase are subject to feedback inhibition by methionine - an additional regulator over those observed for the enzymes from Mycobacterium smegmatis. Intact mycobacterium incorporated carbon from [U-14C]aspartate into the aspartate family of amino acids (threonine, isoleucine, methionine and lysine) though the rate of incorporation in M. avium grown in vivo was about half that in M. avium grown axenically.