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)

Cerulenin, an antifungal antibiotic isolated from a culture filtrate of Cephalosporium caerulens, is a potent inhibitor of fatty acid synthetase systems of various microorganisms and animal tissues. This antibiotic specifically blocks the activity of beta-ketoacyl thioester synthetase (condensing enzyme) by binding to the functional cysteine-SH in the active center of the condensing enzyme domain (the peripheral SH-group). However, fatty acid synthetase from C. caerulens is much less sensitive to cerulenin than fatty acid synthetases from other sources. The properties of C. caerulens synthetase were investigated and compared to those of Saccharomyces cerevisiae synthetase, which is sensitive to the antibiotic. The molecular weight of the enzymically active form of C. caerulens synthetase was 2.53 X 10(6). The enzyme consisted of two multifunctional proteins, alpha and beta, which are arranged in a complex, alpha 6 beta 6. The synthetase was inactivated by iodoacetamide. At 0 degrees C and pH 7.15, the second-order rate constant of k = 15.6 M-1 X s-1 was obtained for the inactivation by iodoacetamide. This value was about 15 times greater than that for S. cerevisiae synthetase. Treatment of C. caerulens synthetase with iodoacetamide, while impairing the synthetase activity, induced malonyl-CoA decarboxylase activity. When S. cerevisiae synthetase was preincubated with cerulenin, malonyl-CoA decarboxylase activity could not be detected even after treatment of the enzyme with iodoacetamide (Kawaguchi, A., Tomoda, H., Nozoe, S., Omura, S., & Okuda, S. (1982) J. Biochem. 92, 7-12). In the case of C. caerulens synthetase, on the other hand, malonyl-CoA decarboxylase activity was induced by iodoacetamide even after the preincubation of the enzyme with cerulenin.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Cerulenin resistance in a cerulenin-producing fungus. II. Characterization of fatty acid synthetase from Cephalosporium caerulens. 638 75

Cerulenin, an antifungal antibiotic produced by Cephalosporium caerulens, is a potent inhibitor of fatty acid synthase in various organisms, including Saccharomyces cerevisiae. The antibiotic inhibits the enzyme by binding covalently to the active center cysteine of the condensing enzyme domain. We isolated 12 cerulenin-resistant mutants of S. cerevisiae following treatment with ethyl methanesulfonate. The mechanism of cerulenin resistance in one of the mutants, KNCR-1, was studied. Growth of the mutant was over 20 times more resistant to cerulenin than that of the wild-type strain. Tetrad analysis suggested that all mutants mapped at the same locus, FAS2, the gene encoding the alpha subunit of the fatty acid synthase. The isolated fatty acid synthase, purified from the mutant KNCR-1, was highly resistant to cerulenin. The cerulenin concentration causing 50% inhibition (IC50) of the enzyme activity was measured to be 400 microM, whereas the IC50 value was 15 microM for the enzyme isolated from the wild-type strain, indicating a 30-fold increase in resistance to cerulenin. The FAS2 gene was cloned from the mutant. Sequence replacement experiments suggested that an 0.8 kb EcoRV-HindIII fragment closely correlated with cerulenin resistance. Sequence analysis of this region revealed that the GGT codon encoding Gly-1257 of the FAS2 gene was altered to AGT in the mutant, resulting in the codon for Ser. Furthermore, a recombinant FAS2 gene, in which the 0.8 Kb EcoRV-HindIII fragment of the wild-type FAS2 gene was replaced with the same region from the mutant, when introduced into FAS2-defective S. cerevisiae complemented the FAS2 phenotype and showed cerulenin resistance.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Cerulenin-resistant mutants of Saccharomyces cerevisiae with an altered fatty acid synthase gene. 804 67