title: Origin-specific DNA-binding membrane-associated protein may be involved in repression of initiation of DNA replication in Bacillus subtilis.
abstract: Previous binding studies with labeled double-stranded Bacillus subtilis DNA fragments to a protein blot of renatured Bacillus membrane proteins showed selective binding of two adjacent origin fragments to a 64-kDa protein. The selective binding of the 64-kDa protein could be blocked by prior incubation of the blots with a specific polyclonal antibody. An in vitro replication system derived from a B. subtilis DNA-membrane complex showed initiation activity without addition of exogenous enzymes or template. When the complex was first incubated with the 64-kDa antibody or with its Fab fragments, initiation activity was enhanced. Antibodies to several other Bacillus membrane proteins as well as nonspecific antibodies did not show any significant stimulatory effect. A heavy-density-label experiment indicated that the complex initiated multiple rounds of replication in the presence of the 64-kDa antibody but not in its absence. The 64-kDa antibody plus an initiation inhibitor (streptovaricin) showed only repair and elongation activity. The 64-kDa protein may act in vivo as a repressor/regulator of initiation activity.
mesh_terms: D000907:Antibodies, Bacterial / Q000276:immunology; D001412:Bacillus subtilis / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D001667:Binding, Competitive; D002499:Centrifugation, Density Gradient; D004261:DNA Replication; D004269:DNA, Bacterial / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism / Q000502:physiology*
chemical_list: D000907:Antibodies, Bacterial; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D008565:Membrane Proteins