HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Ciampi, M. S. Search for Related Content PubMed PubMed Citation Articles by Ciampi, M. S. Agricola Articles by Ciampi, M. S.

Rho-dependent terminators and transcription termination

Dipartimento di Genetica e Microbiologia, Università di Bari, Via Amendola 165/A, 70126 Bari, Italy

Correspondence
M. Sofia Ciampi
ciampi{at}biologia.uniba.it

Rho-dependent transcription terminators participate in sophisticated genetic regulatory mechanisms, in both bacteria and phages; they occur in regulatory regions preceding the coding sequences of genes and within coding sequences, as well as at the end of transcriptional units, to prevent readthrough transcription. Most Rho-dependent terminators have been found in enteric bacteria, but they also occur in Gram-positive bacteria and may be widespread among bacteria. Rho-dependent termination requires both cis-acting elements, on the mRNA, and trans-acting factors. The only cis-acting element common to Rho-dependent terminators is richness in rC residues. Additional sequence elements have been observed at different Rho termination sites. These ‘auxiliary elements' may assist in the termination process; they differ among terminators, their occurrence possibly depending on the function and sequence context of the terminator. Specific nucleotides required for termination have also been identified at Rho sites. Rho is the main factor required for termination; it is a ring-shaped hexameric protein with ATPase and helicase activities. NusG, NusA and NusB are additional factors participating in the termination process. Rho-dependent termination occurs by binding of Rho to ribosome-free mRNA, C-rich sites being good candidates for binding. Rho's ATPase is activated by Rho–mRNA binding, and provides the energy for Rho translocation along the mRNA; translocation requires sliding of the message into the central hole of the hexamer. When a polymerase pause site is encountered, the actual termination occurs, and the transcript is released by Rho's helicase activity. Many aspects of this process are still being studied. The isolation of mutants suppressing termination, site-directed mutagenesis of cis-acting elements in Rho-dependent termination, and biochemistry, are and will be contributing to unravelling the still undefined aspects of the Rho termination machinery. Analysis of the more sophisticated regulatory mechanisms relying on Rho-dependent termination may be crucial in identifying new essential elements for termination.

This article has been cited by other articles:

				C. J. Cardinale, R. S. Washburn, V. R. Tadigotla, L. M. Brown, M. E. Gottesman, and E. Nudler Termination Factor Rho and Its Cofactors NusA and NusG Silence Foreign DNA in E. coli Science, May 16, 2008; 320(5878): 935 - 938. [Abstract] [Full Text] [PDF]

				T. J. Santangelo, L. Cubonova, R. Matsumi, H. Atomi, T. Imanaka, and J. N. Reeve Polarity in Archaeal Operon Transcription in Thermococcus kodakaraensis J. Bacteriol., March 15, 2008; 190(6): 2244 - 2248. [Abstract] [Full Text] [PDF]

				D. S. Gilmour and R. Fan Derailing the Locomotive: Transcription Termination J. Biol. Chem., January 11, 2008; 283(2): 661 - 664. [Full Text] [PDF]

				A. Schwartz, E. Margeat, A. R. Rahmouni, and M. Boudvillain Transcription Termination Factor Rho Can Displace Streptavidin from Biotinylated RNA J. Biol. Chem., October 26, 2007; 282(43): 31469 - 31476. [Abstract] [Full Text] [PDF]