title: The transcriptional regulator Rok binds A+T-rich DNA and is involved in repression of a mobile genetic element in Bacillus subtilis.
abstract: The rok gene of Bacillus subtilis was identified as a negative regulator of competence development. It also controls expression of several genes not related to competence. We found that Rok binds to extended regions of the B. subtilis genome. These regions are characterized by a high A+T content and are known or believed to have been acquired by horizontal gene transfer. Some of the Rok binding regions are in known mobile genetic elements. A deletion of rok resulted in higher excision of one such element, ICEBs1, a conjugative transposon found integrated in the B. subtilis genome. When expressed in the Gram negative E. coli, Rok also associated with A+T-rich DNA and a conserved C-terminal region of Rok contributed to this association. Together with previous work, our findings indicate that Rok is a nucleoid associated protein that serves to help repress expression of A+T-rich genes, many of which appear to have been acquired by horizontal gene transfer. In these ways, Rok appears to be functionally analogous to H-NS, a nucleoid associated protein found in Gram negative bacteria and Lsr2 of high G+C Mycobacteria.
authors.affiliation: Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America.
authors.forename: Wiep Klaas
authors.initials: WK
authors.lastname: Smits
authors.forename: Alan D
authors.initials: AD
authors.lastname: Grossman
mesh_terms: D020856:AT Rich Sequence / Q000235:genetics*; D001412:Bacillus subtilis / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002876:Chromosomes, Bacterial / Q000378:metabolism; D004269:DNA, Bacterial / Q000378:metabolism*; D004926:Escherichia coli; D005453:Fluorescence; D005798:Genes, Bacterial / Q000235:genetics; D020071:Interspersed Repetitive Sequences / Q000235:genetics*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins