Vivian JP, Porter CJ, Wilce JA, Wilce MCJ. An asymmetric structure of the Bacillus subtilis replication terminator protein in complex with DNA.
J Mol Biol 2007;
370:481-91. [PMID:
17521668 DOI:
10.1016/j.jmb.2007.02.067]
[Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Revised: 02/08/2007] [Accepted: 02/17/2007] [Indexed: 11/25/2022]
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.
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