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Centromere pairing by a plasmid-encoded type I ParB protein

Lookup NU author(s): Professor Kenn Gerdes

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Abstract

The par2 locus of Escherichia coli plasmid pB171 encodes two trans-acting proteins, ParA and ParB, and two cis-acting sites, parC1 and parC2, to which ParB binds cooperatively. ParA is related to MinD and oscillates in helical structures and thereby positions ParB/parC-carrying plasmids regularly over the nucleoid. ParB ribbon-helix-helix dimers bind cooperatively to direct repeats in parC1 and parC2. Using four different assays we obtain solid evidence that ParB can pair parC1- and parC2-encoding DNA fragments in vitro. Convincingly, electron microscopy revealed that ParB mediates binary pairing of parC fragments. In addition to binary complexes, ParB mediated the formation of higher order complexes consisting of several DNA fragments joined by ParB at centromere site parC. N-terminal truncated versions of ParB still possessing specific DNA binding activity were incompetent in pairing, hence identifying the N terminus of ParB as a requirement for ParB-mediated centromere pairing. These observations suggest that centromere pairing is an important intermediate step in plasmid partitioning mediated by the common type I loci. © 2007 by The American Society for Biochemistry and Molecular Biology, Inc.

Publication metadata

Author(s): Ringgaard S, Lowe J, Gerdes K

Publication type: Article

Publication status: Published

Journal: Journal of Biological Chemistry

Year: 2007

Volume: 282

Issue: 38

Pages: 28216-28225

ISSN (print): 0021-9258

ISSN (electronic): 1083-351X

Publisher: American Society for Biochemistry and Molecular Biology

URL: http://dx.doi.org/10.1074/jbc.M703733200

DOI: 10.1074/jbc.M703733200

PubMed id: 17644524

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