The Staphylococcus aureus chromsomal gene placC, indentified by mutations amplifying plasmid pT181, encodes a sigma factor

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 slgma factor of Bacillus subtllls, slgA, 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 serlne 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. © 1991 Oxford University Press.