Abstract

Regulation of enzyme synthesis in the tryptophan pathway of Acinetobacter calcoaceticus. W Cohn and I P Crawford ABSTRACT In Acinetobacter calcoaceticus the seven genes coding for the enzymes responsible for tryptophan synthesis map at three chromosomal locations. Two three-gene clusters, one (trpGDC) specifying the small subunit of anthranilate synthase, phosphoribosyl transferase, and indoleglycerol phosphate synthase and the other (trpFBA) specifying phosphoribosyl anthranilate isomerase and both tryptophan synthase subunits, are not linked to each other or to the trpE gene specifying the large anthranilate synthase subunit. When regulation of trp gene expression is studied in the wild type, only the level of the trpF gene product decreases upon addition of tryptophan to the medium. Tryptophan starvation of tryptophan auxotrophs, however, results in increased levels of all the tryptophan enzymes; this and additional evidence suggests that the expression of all the trp genes is subject to repression. The trpGDC genes are coordinately controlled, and the trpE gene is regulated in parallel with them. The trpFBA genes are controlled neither coordinately nor in parallel with the other trp genes, but respond proportionally when compared with each other. So far, two types of constitutive mutants have been found. The first class of mutants apparently occurs in the structural gene for a repressor protein; this repressor locus is unlinked to any of the biosynthetic trp genes and affects only the expression of trpE and the trpGDC cluster. The second class contains mutants closely linked to the trpGDC region; they overproduce only the gene products of this cluster. CiteULike Connotea Delicious Digg Facebook Google+ Mendeley Reddit StumbleUpon Twitter What's this? « Previous | Next Article » Table of Contents This Article J. Bacteriol. July 1976 vol. 127 no. 1 367-379 » Abstract PDF Classifications Research Article Services Email this article to a colleague Similar articles in ASM journals Alert me when this article is cited Alert me if a correction is posted Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of JB Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Load citing article information Citing articles via Web of Science Citing articles via Google Scholar Google Scholar Articles by Cohn, W. Articles by Crawford, I. P. Search for related content PubMed PubMed citation Articles by Cohn, W. Articles by Crawford, I. P. Related Content Load related web page information Social Bookmarking CiteULike Connotea Delicious Digg Facebook Google+ Mendeley Reddit StumbleUpon Twitter What's this? current issue January 2012, volume 194, issue 1 Alert me to new issues of JB About JB Subscribers Authors Reviewers Advertisers Inquiries from the Press Permissions & Commercial Reprints ASM Journals Public Access Policy JB RSS Feeds 1752 N Street N.W. • Washington DC 20036 202.737.3600 • 202.942.9355 fax • journals@asmusa.org Print ISSN: 0021-9193 Online ISSN: 1098-5530 Copyright © 2011 by the American Society for Microbiology. For an alternate route to JB .asm.org, visit: http://intl- JB .asm.org | More Info» var gaJsHost = (("https:" == document.location.protocol) ? "https://ssl." : "http://www."); document.write(unescape("%3Cscript src='" + gaJsHost + "google-analytics.com/ga.js' type='text/javascript'%3E%3C/script%3E")); var pageTracker = _gat._getTracker("UA-5821458-9"); pageTracker._trackPageview();