Rho and RNA: models for recognition and response.
Escherichia coli Rho factor is required for termination of transcription at certain sites by RNA polymerase. Binding to unstructured cytosine-containing RNA target sites, subsequent RNA-dependent ATP hydrolysis, and an RNA-DNA helicase activity that presumably facilitates termination, are considered essential for Rho function. Yet the RNA recognition elements have remained elusive, the parameters relating RNA binding to ATPase activation have been obscure, and the mechanistic steps that integrate Rho's characteristics with its termination function in vitro and in vivo have been largely undefined. Recent work offers new insights into these interactions with results that are both surprising and satisfying in the context of Rho's emerging structure. These include the requirements for binding and ATPase activation by a variety of RNA substrates, dynamic analyses of Rho tracking, helicase and termination activity, and the participation of a new factor (NusG) that interacts with Rho. Models for Rho function are considered in the light of these recent revelations.
Platt
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Department of Biochemistry, University of Rochester Medical Center, New York 14642.
D001426:Bacterial Proteins / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D008957:Models, Genetic; D010445:Peptide Elongation Factors / Q000378:metabolism; D012234:Rho Factor / Q000378:metabolism*; D013728:Terminator Regions, Genetic; D014157:Transcription Factors; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C070291:NusG protein, E coli; D010445:Peptide Elongation Factors; D012234:Rho Factor; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases