2ntz
Structure of a ParB-DNA complex reveals a double B-box interaction
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe plasmid partition process is essential for plasmid propagation and is mediated by par systems, consisting of centromere-like sites and two proteins, ParA and ParB. In the first step of partition by the archetypical P1 system, ParB binds a complicated centromere-like site to form a large nucleoprotein segrosome. ParB is a dimeric DNA-binding protein that can bridge between both A-boxes and B-boxes located on the centromere. Its helix-turn-helix domains bind A-boxes and the dimer domain binds B-boxes. Binding of the first ParB dimer nucleates the remaining ParB molecules onto the centromere site, which somehow leads to the formation of a condensed segrosome superstructure. To further understand this unique DNA spreading capability of ParB, we crystallized and determined the structure of a 1:2 ParB-(142-333):A3-B2-box complex to 3.35A resolution. The structure reveals a remarkable four-way, protein-DNA bridged complex in which both ParB helix-turn-helix domains simultaneously bind adjacent A-boxes and the dimer domain bridges between two B-boxes. The multibridging capability and the novel dimer domain-B-box interaction, which juxtaposes the DNA sites close in space, suggests a mechanism for the formation of the wrapped solenoid-like segrosome superstructure. This multibridging capability of ParB is likely critical in its partition complex formation and pairing functions. Structure of a four-way bridged ParB-DNA complex provides insight into P1 segrosome assembly.,Schumacher MA, Mansoor A, Funnell BE J Biol Chem. 2007 Apr 6;282(14):10456-64. Epub 2007 Feb 9. PMID:17293348[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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