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Updated: Aug 15, 2026

Methodology for the Study of Horizontal Gene Transfer in Staphylococcus aureus
Published on: March 10, 2017
The Staphylococcus aureus chromosomal gene plaC, identified by mutations amplifying plasmid pT181, encodes a sigma
1Public Health Research Institute, New York, NY 10016.
Abstract:
The Staphylococcus aureus chromosomal gene plaC, identified by mutations such as plaC1 that lead to the amplification of plasmid pT181, has been cloned and sequenced. The plaC gene encodes a protein with high similarity (79% identity) with the vegetative sigma factor of Bacillus subtilis, sigA, suggesting that it acts as an RNA polymerase sigma factor in S.aureus. The plaC1 mutation was found to be a C to T transition leading to a proline to serine substitution at amino acid residue 209 of the protein. In other sigma factors this region of the protein is involved in specific recognition of the -10 promoter sequence. The change in sigma factor activity due to this mutation is characterized by its strict specificity for a limited number of promoters and the rather high amplitude of the effect.
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