Centromere pairing by a plasmid-encoded type I ParB protein

Simon Ringgaard, Jan Lowe, Kenn Gerdes

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

22 Citationer (Scopus)

Abstract

Thepar2 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.
OriginalsprogEngelsk
TidsskriftJournal of Biological Chemistry
Vol/bind282
Udgave nummer38
Sider (fra-til)28216-28225
Antal sider10
ISSN0021-9258
DOI
StatusUdgivet - 2007
Udgivet eksterntJa

Citationsformater