Document Detail

Repair system for noncanonical purines in Escherichia coli.
MedLine Citation:
PMID:  12730170     Owner:  NLM     Status:  MEDLINE    
Exposure of Escherichia coli strains deficient in molybdopterin biosynthesis (moa) to the purine base N-6-hydroxylaminopurine (HAP) is mutagenic and toxic. We show that moa mutants exposed to HAP also exhibit elevated mutagenesis, a hyperrecombination phenotype, and increased SOS induction. The E. coli rdgB gene encodes a protein homologous to a deoxyribonucleotide triphosphate pyrophosphatase from Methanococcus jannaschii that shows a preference for purine base analogs. moa rdgB mutants are extremely sensitive to killing by HAP and exhibit increased mutagenesis, recombination, and SOS induction upon HAP exposure. Disruption of the endonuclease V gene, nfi, rescues the HAP sensitivity displayed by moa and moa rdgB mutants and reduces the level of recombination and SOS induction, but it increases the level of mutagenesis. Our results suggest that endonuclease V incision of DNA containing HAP leads to increased recombination and SOS induction and even cell death. Double-strand break repair mutants display an increase in HAP sensitivity, which can be reversed by an nfi mutation. This suggests that cell killing may result from an increase in double-strand breaks generated when replication forks encounter endonuclease V-nicked DNA. We propose a pathway for the removal of HAP from purine pools, from deoxynucleotide triphosphate pools, and from DNA, and we suggest a general model for excluding purine base analogs from DNA. The system for HAP removal consists of a molybdoenzyme, thought to detoxify HAP, a deoxyribonucleotide triphosphate pyrophosphatase that removes noncanonical deoxyribonucleotide triphosphates from replication precursor pools, and an endonuclease that initiates the removal of HAP from DNA.
Nicholas E Burgis; Jason J Brucker; Richard P Cunningham
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of bacteriology     Volume:  185     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  2003 May 
Date Detail:
Created Date:  2003-05-05     Completed Date:  2003-06-16     Revised Date:  2013-06-09    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  3101-10     Citation Subset:  IM    
Department of Biological Sciences, The University at Albany, State University of New York, Albany, New York 12222, USA.
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MeSH Terms
Adenine / analogs & derivatives*,  metabolism*,  pharmacology
Bacterial Proteins / genetics
Chromosome Breakage
DNA / genetics,  metabolism
DNA Repair / physiology*
DNA Replication
Deoxyribonuclease (Pyrimidine Dimer)
Endodeoxyribonucleases / metabolism
Escherichia coli / drug effects,  genetics*,  metabolism
Escherichia coli Proteins / drug effects,  genetics,  metabolism
Metalloproteins / biosynthesis,  genetics
Purines / metabolism*
Pyrophosphatases / drug effects,  genetics,  metabolism
Recombination, Genetic
SOS Response (Genetics) / drug effects
Serine Endopeptidases / genetics
Reg. No./Substance:
0/Bacterial Proteins; 0/Coenzymes; 0/Escherichia coli Proteins; 0/LexA protein, Bacteria; 0/Metalloproteins; 0/Mutagens; 0/Pteridines; 0/Purines; 5667-20-9/6-N-hydroxylaminopurine; 73-24-5/Adenine; 73508-07-3/molybdenum cofactor; 9007-49-2/DNA; EC 3.1.-/Endodeoxyribonucleases; EC (Pyrimidine Dimer); EC 3.4.21.-/Serine Endopeptidases; EC 3.6.1.-/Pyrophosphatases; EC 3.6.1.-/RdgB protein, E coli

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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