An asymmetric structure of the bacillus subtilis replication terminator protein in complex with DNA

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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.
Original languageEnglish
Pages (from-to)481 - 491
Number of pages11
JournalJournal of Molecular Biology
Volume370
Issue number3
Publication statusPublished - 2007

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