J. Bacteriol., May 1995, 2609-2614, Vol 177, No. 10
L Rao, RK Karls and MJ Betley
The RNA polymerase (RNAP) holoenzyme of Staphylococcus aureus was purified
by DNA affinity, gel filtration, and ion-exchange chromatography. This RNAP
contained four major subunits with apparent molecular masses of 165, 130,
60, and 47 kDa. All four subunits of the RNAP were serologically related to
the subunits of Escherichia coli E sigma 70 holoenzyme by Western
immunoblot analysis. The 60-kDa subunit was subsequently isolated and found
to react with a monoclonal antibody specific to the E. coli sigma 70
subunit. This sigma 70-related protein allowed E. coli core RNAP
promoter-specific initiation and increased transcription by S. aureus RNAP
that is unsaturated with sigma. We therefore suggest that this 60-kDa
protein is a sigma factor. Purified S. aureus RNAP transcribed from the
promoters of several important S. aureus virulence genes (sea, sec, hla,
and agr P2) in vitro. The in vitro transcription start sites of the sea,
sec, and agr P2 promoters, mapped by primer extension, were similar to
those identified in vivo. The putative promoter hexamers of these three
genes showed strong sequence similarity to the E. coli sigma 70 consensus
promoter, and transcription by E sigma 70 from some of these promoters has
been observed. Conversely, S. aureus RNAP does not transcribe from all E.
coli sigma 70-dependent promoters. Taken together, our results indicate
that the promoter sequences recognized by purified S. aureus RNAP are
similar but not identical to those recognized by E. coli E sigma 70.
Copyright © 1995, American Society for Microbiology
In vitro transcription of pathogenesis-related genes by purified RNA polymerase from Staphylococcus aureus
Department of Bacteriology, University of Wisconsin-Madison 53706, USA.
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