Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.3.1 (citrate synthase)
 4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

After a prototrophic strain of Staphylococcus aureus had been exposed to diethyl sulfate, 28 isoleucine- and isoleucine-valine-dependent mutants (ilv mutants) were isolated. On the basis of auxanography, their ability to accumulate intermediates of isoleucine and valine biosynthesis, and intergeneric syntrophism with ilv mutants of Salmonella typhimurium, all mutants were placed into four groups, each of which corresponded to a presumed enzymatic deficiency, as follows: group A, deficient in l-threonine deaminase; group B, deficient in the condensing enzyme; group C, deficient in reductoisomerase; group D, deficient in alpha-beta-dihydroxy acid dehydrase. No mutants blocked in the terminal (transaminase) reactions were isolated. Transduction analyses (best-fit, ratio, and complementation tests) with the use of phage 83 established that the linear arrangement of the structural genes is identical with the order of participation of their enzymes in isoleucine and valine biosynthesis, and that these genes comprise a single linkage group which can exist on a single donor fragment during transduction.
 ...
PMID:Biochemical and genetic analysis of isoleucine and valine biosynthesis in Staphylococcus aureus. 602 2

Ramakrishnan, T. (Yale University, New Haven, Conn.), and Edward A. Adelberg. Regulatory mechanisms in the biosynthesis of isoleucine and valine. I. Genetic derepression of enzyme formation. J. Bacteriol. 87:566-573. 1964.-A total of 60 mutants of Escherichia coli K-12 resistant to 10(-2)m valine were isolated from the valine-sensitive F' strain AB1206. Conjugation experiments showed that in five of these mutants the valine-resistance locus is closely linked to the structural genes governing isoleucine-valine biosynthesis. In these five valine-resistant mutants, three enzymes of the isoleucine-valine pathway were found to be coordinately derepressed: l-threonine deaminase, dihydroxy acid dehydrase, and transaminase B. Two other enzymes of this pathway, the condensing enzyme and the reductoisomerase, were unaffected. The mutation from valine-sensitivity to valine-resistance appears to have altered an operator locus, because the derepressed state is dominant over the repressed state in diploids heterozygous for the valine-resistance locus. The valine-resistant mutants excrete isoleucine into the medium. The significance of these findings with respect to the valine-sensitivity of E. coli K-12 and the regulation of the biosynthesis of isoleucine and valine by this organism are discussed.
 ...
PMID:REGULATORY MECHANISMS IN THE BIOSYNTHESIS OF ISOLEUCINE AND VALINE. I. GENETIC DEREPRESSION OF ENZYME FORMATION. 1412 71