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Journal of Bacteriology, April 1999, p. 2492-2500, Vol. 181, No. 8
Department of Microbiology, Molecular
Genetics and Immunology, University of Kansas Medical Center,
Kansas City, Kansas 66160
Received 30 October 1998/Accepted 1 February 1999
The production of type 8 capsular polysaccharide (CP8) in
Staphylococcus aureus is regulated in response to a variety
of environmental factors. The cap8 genes required for the
CP8 production in strain Becker are transcribed as a single large
transcript by a primary promoter located within a 0.45-kb region
upstream of the first gene of the cap8 gene cluster. In
this study, we analyzed the primary cap8 promoter region in
detail. We determined the transcription initiation site of the primary
transcript by primer extension and identified the potential promoter
sequences. We found several inverted and direct repeats upstream of the
promoter. Deletion analysis and site-directed mutagenesis showed that a
10-bp inverted repeat of one of the repeats was required for promoter
activity. We showed that the distance but not the specific sequences
between the inverted repeat and the promoter was critical to the
promoter activity. However, insertion of a DNA sequence with two or
four helix turns in this intervening region had a slight effect on promoter activity. To demonstrate the biological significance of the
10-bp inverted repeat, we constructed a strain with a mutation in the
repeat in the S. aureus Becker chromosome and showed that the repeat affected CP8 production mostly at the transcriptional level.
By gel mobility shift assay, we demonstrated that strain Becker
produced at least one protein capable of specific binding to the 10-bp
inverted repeat, indicating that the repeat serves as a positive
regulatory protein binding site. In addition, reporter gene fusion
analysis showed that the cap8 promoter activity was influenced by various growth media and affected most by yeast extract.
Our results suggest that yeast extract may exert its profound
inhibitory effect on cap8 gene expression through the 10-bp
inverted repeat element.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Promoter Analysis of the cap8 Operon, Involved in Type
8 Capsular Polysaccharide Production in Staphylococcus
aureus
and
*
Corresponding author. Mailing address: Department of
Microbiology, Molecular Genetics and Immunology, Room 3025 WHW,
University of Kansas Medical Center, 3901 Rainbow Blvd., Kansas City,
KS 66160. Phone: (913) 588-7156. Fax: (913) 588-7295. E-mail:
clee{at}kumc.edu.
Present address: Bangalore Genei Pvt. Ltd., Peenya, Bangalore
560058, India.
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