Studies on the biosynthesis of thiostrepton: 4-(1- hydroxyethyl)quinoline-2-carboxylate as a free intermediate on the pathway to the quinaldic acid moiety

Nigel D. Priestley, Todd M. Smith, Paul R. Shipley, Heinz G. Floss

Research output: Contribution to journalArticlepeer-review

37 Scopus citations

Abstract

Specifically 13C-labeled quinoline-2-carboxylate derivatives were synthesized from quinoline and used to study the biosynthesis of thiostrepton in a strain of Streptomyces laurentii. 13C NMR analysis of thiostrepton recovered after feeding methyl (RS)-[11-13C]-4-(1-hydroxyethyl)quinoline- 2-carboxylate or methyl [11-13C]-4-acetylquinoline-2-carboxylate showed conclusively that these compounds are specifically and efficiently incorporated into thiostrepton. Both compounds were also detected in cultures of the producing organism by isotope dilution analysis. The significance of the relative endogenous concentrations of the two compounds and of the relative extent of the incorporation of exogenously added labeled material into thiostrepton are discussed in terms of the biosynthetic pathway linking tryptophan and 4-(1-hydroxyethyl)quinoline-2-carboxylate in S. laurentii. A highly specific enzyme activity was detected in cell-free extracts of S. laurentii that was capable of adenylating (12S)-4-(1-hydroxyethyl)quinoline- 2-carboxylic acid. Partial purification of the enzyme was achieved. The enzyme was found to be specific for the enantiomer of the substrate which has the same absolute configuration as found in the natural antibiotic structure. The presence of one specific enzyme catalysing the adenylation process in S. laurentii was shown by photoaffinity labeling with [α-32P]-8-azido-ATP and subsequent SDS PAGE analysis of the labeled products. The native molecular weight of the active enzyme, determined by gel permeation chromatography, was found to be approximately 47 kDa, compared with a denatured weight of 50 kDa estimated for the photoaffinity-labeled protein. The enzyme is thus probably monomeric.

Original languageEnglish
Pages (from-to)1135-1147
Number of pages13
JournalBioorganic and Medicinal Chemistry
Volume4
Issue number7
DOIs
StatePublished - Jul 1996

Fingerprint

Dive into the research topics of 'Studies on the biosynthesis of thiostrepton: 4-(1- hydroxyethyl)quinoline-2-carboxylate as a free intermediate on the pathway to the quinaldic acid moiety'. Together they form a unique fingerprint.

Cite this