Document Detail

DnaB and DnaI temperature-sensitive mutants of Staphylococcus aureus: evidence for involvement of DnaB and DnaI in synchrony regulation of chromosome replication.
MedLine Citation:
PMID:  17906136     Owner:  NLM     Status:  MEDLINE    
DnaB and DnaI proteins conserved in low-GC content Gram-positive bacteria are apparently involved in helicase loading at the replication initiation site and during the restarting of stalled replication forks. In this study, we found five novel dnaB mutants and three novel dnaI mutants by screening 750 temperature-sensitive Gram-positive Staphylococcus aureus mutants. All of the mutants had a single amino acid substitution in either DnaB or DnaI that controlled temperature-sensitive growth, as confirmed by transduction experiments using phage 80alpha. DNA synthesis as measured by [(3)H]thymine incorporation, origin-to-terminus ratios and flow cytometric analysis revealed that the dnaB and dnaI mutants were unable to initiate DNA replication at restrictive temperatures, which is similar to previous findings in Bacillus subtilis. Furthermore, some of the mutants were found to exhibit asynchrony in the initiation of DNA replication. Also, a fraction of the dnaI mutant cells showed arrested replication, and the dnaI mutant tested was sensitive to mitomycin C, which causes DNA lesions. These results suggest that DnaB and DnaI are required not only for replication initiation and but also for regulation of its synchrony, and they provide support for the involvement of DnaI activity in the restart of arrested replication forks in vivo.
Yan Li; Kenji Kurokawa; Luzia Reutimann; Hikaru Mizumura; Miki Matsuo; Kazuhisa Sekimizu
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Microbiology (Reading, England)     Volume:  153     ISSN:  1350-0872     ISO Abbreviation:  Microbiology (Reading, Engl.)     Publication Date:  2007 Oct 
Date Detail:
Created Date:  2007-10-01     Completed Date:  2007-11-27     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9430468     Medline TA:  Microbiology     Country:  England    
Other Details:
Languages:  eng     Pagination:  3370-9     Citation Subset:  IM    
Laboratory of Microbiology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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MeSH Terms
Amino Acid Substitution / genetics
Bacterial Proteins / genetics,  physiology*
Chromosomes, Bacterial*
DNA Replication / genetics,  physiology*
DNA Replication Timing / genetics,  physiology*
DNA, Bacterial / biosynthesis
DnaB Helicases / genetics,  physiology*
Genes, Essential
Mutation, Missense
Staphylococcus Phages
Staphylococcus aureus / genetics,  physiology*
Transcription Factors / genetics,  physiology*
Transduction, Genetic
Reg. No./Substance:
0/Bacterial Proteins; 0/DNA, Bacterial; 0/Transcription Factors; EC 3.1.-/DnaB Helicases

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