University at Buffalo - The State University of New York
Skip to Content
An amino acid change near the carboxyl terminus of the Streptococcus gordonii regulatory protein Rgg affects its abilities to bind DNA and influenc... - PubMed - NCBI
Format

Send to

Choose Destination
See comment in PubMed Commons below
Microbiology. 2003 Feb;149(Pt 2):399-406.

An amino acid change near the carboxyl terminus of the Streptococcus gordonii regulatory protein Rgg affects its abilities to bind DNA and influence expression of the glucosyltransferase gene gtfG.

Author information

1
Department of Oral Surgery and Hospital Dentistry, School of Dentistry, Indiana University, Indianapolis, IN, USA. mvickerm@iupui.edu

Abstract

The Streptococcus gordonii glucosyltransferase structural gene, gtfG, is located immediately downstream from its positive transcriptional regulatory determinant, rgg. Recent genetic studies have indicated that the 3' end of rgg is involved either directly as a binding site or indirectly, e.g. by playing a role in secondary structure, in the interaction of Rgg with the gtfG promoter. A previously identified spontaneous mutant with a point mutation near the 3' end of rgg had only approximately 25% of the parental level of glucosyltransferase activity. To determine if this decreased activity was due to a change in the DNA binding site of trans-acting Rgg, or due to a change in the Rgg protein itself, complementation analyses and DNA-binding studies were performed. In Rgg-deficient strains, the chromosomal rgg point mutation did not influence the ability of plasmid-borne rgg to increase glucosyltransferase expression. However, plasmids carrying parental rgg were able to increase glucosyltransferase activity and expression of a gtfG promoter fusion to a greater extent than plasmids carrying the mutant allele, indicating that the mutant Rgg protein had decreased activity. The ability of NH(2)-terminal (hexahistidine) tagged proteins to bind to a 107 bp dsDNA fragment corresponding to the region immediately upstream of gtfG was demonstrated by surface plasmon resonance. Despite their differences in activity, both mutant and parental recombinant Rgg proteins bound to this dsDNA, albeit with different strengths. These studies provide insights into functional domains of S. gordonii Rgg which influence glucosyltransferase expression, and may have implications for Rgg-like regulatory proteins in related bacteria.

PMID:
12624202
DOI:
10.1099/mic.0.25983-0
[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Ingenta plc
    Loading ...
    Support Center