Affiliation:
1. Department of Pathology, University of Michigan Medical School, Ann Arbor 48109-0602.
Abstract
In Escherichia coli, most of the dUMP that is used as a substrate for thymidylate synthetase is generated from dCTP through the sequential action of dCTP deaminase and dUTPase. Some mutations of the dut (dUTPase) gene are lethal even when the cells are grown in the presence of thymidine, but their lethality can be suppressed by extragenic mutations that can be produced by transposon insertion. Six suppressor mutations were tested, and all were found to belong to the same complementation group. The affected gene was cloned, it was mapped by hybridization with a library of recombinant DNA, and its nucleotide sequence was determined. The gene is at 2,149 kb on the physical map. Its product, a 21.2-kDa polypeptide, was overproduced 1,000-fold via an expression vector and identified as dCTP deaminase, the enzyme affected in previously described dcd mutants. Null mutations in dcd probably suppress the lethality of dut mutations by reducing the accumulation of dUTP, which would otherwise lead to the excessive incorporation of uracil into DNA.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Reference35 articles.
1. Ausubel F. M. R. Brent R. E. Kingston D. D. Moore J. G. Seidman J. A. Smith and K. Struhl (ed.). 1989. Current protocols in molecular biology. John Wiley & Sons Inc. New York.
2. Bachmann B. J. 1987. Derivations and genotypes of some mutant derivatives of Escherichia coli K-12 p. 1190-1219. In F. C. Neidhardt J. L. Ingraham K. B. Low B. Magasanik M. Schaechter and H. E. Umbarger (ed.) Escherichia coli and Salmonella typhimurium: cellular and molecular biology. American Society for Microbiology Washington D.C.
3. Linkage map of Escherichia coli K-12, edition 8;Bachmann B. J.;Microbiol. Rev.,1990
4. Deoxycytidine triphosphate deaminase of Salmonella typhimurium;Beck C. F.;J. Biol. Chem.,1975
5. Complete analysis of cellular nucleotides by two-dimensional thin-layer chromatography;Bochner B. R.;J. Biol. Chem.,1982
Cited by
41 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献