Activity of Yeast Orotidine-5′-phosphate Decarboxylase in the Absence of Metals

Brian G Miller,Jeffrey A Smiley,Steven A Short,Richard Wolfenden

doi:10.1074/jbc.274.34.23841

Abstract

Yeast orotidine-5'-phosphate decarboxylase was recently shown to contain zinc and to be inhibited by zinc-complexing agents. When the gene for the yeast enzyme was expressed in Escherichia coli, the gene product was devoid of metal atoms but exhibited a specific activity and molecular mass similar to those of the enzyme obtained directly from yeast. This invalidates the hypothesis that zinc is involved in substrate decarboxylation. The zinc-free enzyme undergoes thermal inactivation at a somewhat lower temperature than does the zinc-containing enzyme isolated from yeast.

Highlights

Yeast orotidine-5؅-phosphate decarboxylase was recently shown to contain zinc and to be inhibited by zinc-complexing agents
When the gene for the yeast enzyme was expressed in Escherichia coli, the gene product was devoid of metal atoms but exhibited a specific activity and molecular mass similar to those of the enzyme obtained directly from yeast
To investigate the possible role of zinc in the action of ODCase, we used a bacterial system to express the ura[3] gene that encodes yeast ODCase. We find this gene product to be fully active but devoid of metal atoms, invalidating the hypothesis that zinc is involved in catalysis

Summary

Introduction

Yeast orotidine-5؅-phosphate decarboxylase was recently shown to contain zinc and to be inhibited by zinc-complexing agents. When the gene for the yeast enzyme was expressed in Escherichia coli, the gene product was devoid of metal atoms but exhibited a specific activity and molecular mass similar to those of the enzyme obtained directly from yeast. To investigate the possible role of zinc in the action of ODCase, we used a bacterial system to express the ura[3] gene that encodes yeast ODCase.

Results

Conclusion