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Journal of Bacteriology, May 2004, p. 2829-2840, Vol. 186, No. 9
0021-9193/04/$08.00+0     DOI: 10.1128/JB.186.9.2829-2840.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.

Highly Divergent RfaH Orthologs from Pathogenic Proteobacteria Can Substitute for Escherichia coli RfaH both In Vivo and In Vitro

Heather D. Carter, Vladimir Svetlov, and Irina Artsimovitch*

Department of Microbiology, The Ohio State University, Columbus, Ohio 43210

Received 18 November 2003/ Accepted 14 January 2004

The transcriptional enhancer protein RfaH positively regulates production of virulence factors in Escherichia coli and Salmonella enterica serovar Typhimurium via a cis element, ops. Genes coding for RfaH orthologs were identified in conceptually translated genomes of bacterial pathogens, including Vibrio and Yersinia spp. We cloned the rfaH genes from Vibrio cholerae, Yersinia enterocolitica, S. enterica serovar Typhimurium, and Klebsiella pneumoniae into E. coli expression vectors. Purified RfaH orthologs, including the most divergent one from V. cholerae, were readily recruited to the E. coli transcription elongation complex. Postrecruitment stimulation of transcript elongation appeared to vary with the degree of similarity to E. coli RfaH. V. cholerae RfaH was particularly defective in reducing downstream pausing and termination; this defect was substantially alleviated by an increase in its concentration. When overexpressed episomally, all of the rfaH genes complemented the disruption of the chromosomal copy of the E. coli gene. Thus, despite the apparently accelerated divergent evolution of the RfaH proteins, the mechanism of their action is conserved well enough to make them transcriptionally active in the E. coli system.

* Corresponding author. Mailing address: Department of Microbiology, The Ohio State University, 376 BioSciences Building., 484 West 12th Ave., Columbus, OH 43210. Phone: (614) 292-6777. Fax: (614) 292-8120. E-mail: artsimovitch.1{at}osu.edu.

Journal of Bacteriology, May 2004, p. 2829-2840, Vol. 186, No. 9
0021-9193/04/$08.00+0     DOI: 10.1128/JB.186.9.2829-2840.2004
Copyright © 2004, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Sevostyanova, A., Svetlov, V., Vassylyev, D. G., Artsimovitch, I. (2008). The elongation factor RfaH and the initiation factor {sigma} bind to the same site on the transcription elongation complex. Proc. Natl. Acad. Sci. USA 105: 865-870 [Abstract] [Full Text]  
  • Svetlov, V., Belogurov, G. A., Shabrova, E., Vassylyev, D. G., Artsimovitch, I. (2007). Allosteric control of the RNA polymerase by the elongation factor RfaH. Nucleic Acids Res 35: 5694-5705 [Abstract] [Full Text]  
  • Nagy, G., Danino, V., Dobrindt, U., Pallen, M., Chaudhuri, R., Emody, L., Hinton, J. C., Hacker, J. (2006). Down-Regulation of Key Virulence Factors Makes the Salmonella enterica Serovar Typhimurium rfaH Mutant a Promising Live-Attenuated Vaccine Candidate.. Infect. Immun. 74: 5914-5925 [Abstract] [Full Text]  


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