Investigation of the early steps of molybdopterin biosynthesis in Escherichia coli through the use of in vivo labeling studies.

Published

Journal Article

The early steps in the biosynthesis of the molybdopterin portion of the molybdenum cofactor have been investigated through the use of radiolabeled precursors. Labeled guanosine was added to growing cultures of the molybdopterin-deficient Escherichia coli mutant, moeB, which accumulates large amounts of precursor Z, the final intermediate in molybdopterin biosynthesis (Wuebbens, M. M., and Rajagopalan, K. V. (1993) J. Biol. Chem. 268, 13493-13498). Precursor Z is readily oxidized to the stable, fluorescent pterin, compound Z, which contains all 10 of the carbon atoms present in molybdopterin. For these experiments, compound Z was isolated from both the cells and culture media and analyzed for the presence of label. The development of a method for sequential cleavage of the compound Z side chain carbons facilitated determination of the distribution of label between the ring and the side chain of compound Z. Addition of uniformly labeled [14C]guanosine to moeB cultures produced compound Z labeled in both the ring and the side chain. Growth on [8-14C]guanosine resulted in transfer of label to the C-1' position of compound Z. The label present in compound Z purified from cultures grown on [8,5'-3H]guanosine was lost by removal of the three terminal side chain carbons. These results indicate that although a guanosine compound serves as the initial precursor for molybdopterin biosynthesis, the early steps of this pathway in E. coli proceed via a pathway unlike that of any known pteridine biosynthetic pathway.

Full Text

Duke Authors

Cited Authors

  • Wuebbens, MM; Rajagopalan, KV

Published Date

  • January 20, 1995

Published In

Volume / Issue

  • 270 / 3

Start / End Page

  • 1082 - 1087

PubMed ID

  • 7836363

Pubmed Central ID

  • 7836363

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.270.3.1082

Language

  • eng

Conference Location

  • United States