This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Klimpel, K W Articles by Clark, V L Search for Related Content PubMed PubMed Citation Articles by Klimpel, K W Articles by Clark, V L

research-article

Identification of subunits of gonococcal RNA polymerase by immunoblot analysis: evidence for multiple sigma factors.

Department of Microbiology and Immunology, University of Rochester, New York 14642.

ABSTRACT

Heparin-agarose and single-stranded DNA-cellulose chromatography were used to purify RNA polymerase 25-fold from Neisseria gonorrhoeae, and the activity of the polymerase was characterized in altered assay systems. The core subunits (beta, beta', and alpha) were tentatively identified as major proteins copurifying with polymerase activity. The identification of the core subunits was confirmed by Western (immunoblot) analysis with polyclonal antisera to Escherichia coli core RNA polymerase. Gonococcal sigma factor heterogeneity was examined by Western blot analysis with polyclonal antiserum to the major E. coli sigma factor, sigma 70, to the E. coli heat shock sigma factor, sigma 32, and with a monoclonal antiserum to Salmonella typhimurium NtrA (sigma 54). Purified RNA polymerase and whole-cell extracts from type 1, type 4, heat-shocked, and anaerobically grown gonococci were examined. Four putative gonococcal sigma factors were detected in purified RNA polymerase preparations and in whole-cell extracts from all cell types. Two of these bands appeared as a doublet, which had an estimated Mr of 80,000. A single lower-Mr band, estimated to be 40,000, was also present. All three of these bands reacted with antisera to E. coli sigma 70 and to E. coli sigma 32. A fourth gonococcal protein reacted solely with a highly specific monoclonal antibody to sigma 54 and had an Mr of 90,000. We conclude that N. gonorrhoeae may contain multiple sigma factors, which it may use to regulate gene expression.

This article has been cited by other articles:

• Bittner, M., Saldias, S., Estevez, C., Zaldivar, M., Marolda, C. L., Valvano, M. A., Contreras, I. (2002). O-antigen expression in Salmonella enterica serovar Typhi is regulated by nitrogen availability through RpoN-mediated transcriptional control of the rfaH gene. Microbiology 148: 3789-3799 [Abstract] [Full Text]