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In vitro synthesis of molybdopterin from precursor Z using purified converting factor. Role of protein-bound sulfur in formation of the dithiolene.

Publication ,  Journal Article
Pitterle, DM; Johnson, JL; Rajagopalan, KV
Published in: J Biol Chem
June 25, 1993

The pterin component of the molybdenum cofactor, termed molybdopterin, is synthesized in Escherichia coli by enzymes encoded at the chl loci. A late step in the biosynthetic pathway, the conversion of a molybdopterin intermediate, precursor Z, to molybdopterin, requires the activity of a two-subunit protein, the converting factor. Precursor Z has many of the features of molybdopterin but lacks the dithiolene function essential for molybdenum ligation. Conversion of precursor Z to molybdopterin is accomplished by transfer of sulfur to produce the dithiolene. The present study describes an in vitro system for molybdopterin biosynthesis comprised of purified precursor Z and purified converting factor. It is established that these components are sufficient to yield molybdopterin, identified by conversion to its characteristic products, Form A, Form B, and dicarboxamidomethylmolybdopterin. Under conditions of precursor excess, the formation of molybdopterin was stoichiometric with converting factor, as would be expected in the absence of a sulfur-regenerating system. The labile product of the reaction, molybdopterin, remained associated with the converting factor large subunit. These results establish that the source of sulfur for molybdopterin biosynthesis is the converting factor and suggest that in vivo a novel sulfur cycle must function to resupply sulfur to the converting factor.

Duke Scholars

Published In

J Biol Chem

ISSN

0021-9258

Publication Date

June 25, 1993

Volume

268

Issue

18

Start / End Page

13506 / 13509

Location

United States

Related Subject Headings

  • Sulfurtransferases
  • Sulfur
  • Pteridines
  • Protein Precursors
  • Organophosphorus Compounds
  • Molybdenum Cofactors
  • Metalloproteins
  • Escherichia coli
  • Coenzymes
  • Chromatography, High Pressure Liquid
 

Citation

APA
Chicago
ICMJE
MLA
NLM

Published In

J Biol Chem

ISSN

0021-9258

Publication Date

June 25, 1993

Volume

268

Issue

18

Start / End Page

13506 / 13509

Location

United States

Related Subject Headings

  • Sulfurtransferases
  • Sulfur
  • Pteridines
  • Protein Precursors
  • Organophosphorus Compounds
  • Molybdenum Cofactors
  • Metalloproteins
  • Escherichia coli
  • Coenzymes
  • Chromatography, High Pressure Liquid