E-MEXP-2133 - Chromatin immunoprecipitation of Bacillus subtilis to identify Noc protein binding sites
Submitted on 14 April 2009, released on 1 July 2009, last updated on 27 March 2012
Coordination of chromosome segregation and cytokinesis is crucial for efficient cell proliferation. In Bacillus subtilis the nucleoid occlusion protein Noc protects chromosomes by associating with the chromosome and preventing cell division in its vicinity. Using protein localization, ChAP-on-Chip and bioinformatics, we have identified a consensus Noc-binding DNA sequence (NBS), and show that Noc is targeted to about 70 discrete regions scattered around the chromosome, though absent from a large region around the replication terminus. Purified Noc bound specifically to an NBS in vitro. NBSs inserted near the replication terminus bound Noc-YFP and caused a delay in cell division. An autonomous plasmid carrying an NBS recruited Noc-YFP and conferred a severe Noc-dependent inhibition of cell division. This shows that Noc is a potent inhibitor of division but that its activity is strictly localized by interaction with NBS sites in vivo. We propose that Noc not only serves as a spatial regulator of cell division to protect the nucleoid, but also a timing device with an important role in the co-ordination of chromosome segregation and cell division.
ChIP-chip by array, binding site identification, cell cycle, in vivo, strain or line
Noc protein binds to specific DNA sequences to coordinate cell division with chromosome segregation. Ling Juan Wu, Shu Ishikawa, Yoshikazu Kawai, Taku Oshima, Naotake Ogasawara and Jeff Errington. EMBO J 28(13):1940-1952 (2009), PMID:19494834