Biomaterial Database

Degradation of Escherichia coli DNA: evidence for limitation in vivo by protein X, the recA gene product. 1979

G Satta, and L J Gudas, and A B Pardee

DNA is more extensively degraded after it is damaged in recA mutants of E. coli than in wild type cells. All data presented here are consistent with the recA gene product, protein X, being an inhibitor of nalidixic acid induced degradation of the bulk DNA (but not of newly replicated DNA). Production of protein X also is correlated with appearance of various "S.O.S." repair functions. Evidence was obtained by comparing the rates of protein X synthesis and solubilization of uniformly-labeled DNA in intact cells, incubated in the presence of nalidixic acid. A set of mutants at the lexA locus produced protein X at different rates and degraded their DNA at rates which were inversely correlated to their rates of protein X production. A low concentration of rifampicin quite specifically inhibited protein X production by wild type E. coli, and allowed more rapid DNA degradation. After the DNA was damaged by the incubation of cells in the presence of nalidixic acid, cells preloaded with protein X degraded their DNA more slowly. We propose that protein X could protect DNA against degradation by binding to single-stranded regions, thereby inhibiting nuclease action.

UI	MeSH Term	Description	Entries
D009154	Mutation	Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.	Mutations
D010641	Phenotype	The outward appearance of the individual. It is the product of interactions between genes, and between the GENOTYPE and the environment.	Phenotypes
D004260	DNA Repair	The removal of DNA LESIONS and/or restoration of intact DNA strands without BASE PAIR MISMATCHES, intrastrand or interstrand crosslinks, or discontinuities in the DNA sugar-phosphate backbones.	DNA Damage Response
D004261	DNA Replication	The process by which a DNA molecule is duplicated.	Autonomous Replication,Replication, Autonomous,Autonomous Replications,DNA Replications,Replication, DNA,Replications, Autonomous,Replications, DNA
D004269	DNA, Bacterial	Deoxyribonucleic acid that makes up the genetic material of bacteria.	Bacterial DNA
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D005796	Genes	A category of nucleic acid sequences that function as units of heredity and which code for the basic instructions for the development, reproduction, and maintenance of organisms.	Cistron,Gene,Genetic Materials,Cistrons,Genetic Material,Material, Genetic,Materials, Genetic
D001426	Bacterial Proteins	Proteins found in any species of bacterium.	Bacterial Gene Products,Bacterial Gene Proteins,Gene Products, Bacterial,Bacterial Gene Product,Bacterial Gene Protein,Bacterial Protein,Gene Product, Bacterial,Gene Protein, Bacterial,Gene Proteins, Bacterial,Protein, Bacterial,Proteins, Bacterial