Subcellular localization of Dna-initiation proteins of Bacillus subtilis: evidence that chromosome replication begins at either edge of the nucleoids

Citation
Y. Imai et al., Subcellular localization of Dna-initiation proteins of Bacillus subtilis: evidence that chromosome replication begins at either edge of the nucleoids, MOL MICROB, 36(5), 2000, pp. 1037-1048
Citations number
48
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
36
Issue
5
Year of publication
2000
Pages
1037 - 1048
Database
ISI
SICI code
0950-382X(200006)36:5<1037:SLODPO>2.0.ZU;2-0
Abstract
We examined the intracellular distribution of Bacillus subtilis Dna-initiat ion proteins by immunofluorescence microscopy to visualize the initiation c omplex of replication in vivo. DnaA was distributed throughout the cytoplas m, but both DnaB and DnaI were always detected as foci during the cell-divi sion cycle. Interaction of DnaI with the DnaC helicase by the yeast two-hyb rid assay suggests that DnaI acts as a helicase loader. The number of DnaB and DnaI foci within the cell exceeded that of oriC. Although the foci were not always co-localized with oriC, they seemed to be localized near the ou ter or inner edges of the nucleoids at initiation of replication. When the replication cycle was synchronized in cells using a temperature-sensitive d naA mutant, duplication of the oriC region was observed predominantly near an edge of the nucleoid. Before initiation occurred, each one of the DnaB a nd DnaI foci was frequently observed near there. Furthermore, DnaX-GFP (Dna X is a component of DNA polymerase III) foci were detected near either of t he edges of the nucleoids at the onset of replication. These results sugges t that the replisome is recruited into oriC near either edge of the nucleoi ds to initiate chromosome replication in B. subtilis.