title: An asymmetric structure of the Bacillus subtilis replication terminator protein in complex with DNA.
abstract: In Bacillus subtilis, the termination of DNA replication via polar fork arrest is effected by a specific protein:DNA complex formed between the replication terminator protein (RTP) and DNA terminator sites. We report the crystal structure of a replication terminator protein homologue (RTP.C110S) of B. subtilis in complex with the high affinity component of one of its cognate DNA termination sites, known as the TerI B-site, refined at 2.5 A resolution. The 21 bp RTP:DNA complex displays marked structural asymmetry in both the homodimeric protein and the DNA. This is in contrast to the previously reported complex formed with a symmetrical TerI B-site homologue. The induced asymmetry is consistent with the complex's solution properties as determined using NMR spectroscopy. Concomitant with this asymmetry is variation in the protein:DNA binding pattern for each of the subunits of the RTP homodimer. It is proposed that the asymmetric "wing" positions, as well as other asymmetrical features of the RTP:DNA complex, are critical for the cooperative binding that underlies the mechanism of polar fork arrest at the complete terminator site.
authors.affiliation: Department of Pharmacology, University of Western Australia, Nedlands, Western Australia, 6009, Australia.
authors.forename: J P
authors.initials: JP
authors.lastname: Vivian
authors.forename: C J
authors.initials: CJ
authors.lastname: Porter
authors.forename: J A
authors.initials: JA
authors.lastname: Wilce
authors.forename: M C J
authors.initials: MC
authors.lastname: Wilce
mesh_terms: D001412:Bacillus subtilis / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D018360:Crystallography, X-Ray; D004261:DNA Replication; D004269:DNA, Bacterial / Q000737:chemistry / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; C063112:rtP protein, Bacillus subtilis