|Family type peptidase||M82.001 - PrsW peptidase (Bacillus subtilis), MEROPS Accession MER0057728 (peptidase unit: 15-213)|
|Content of family||Peptidase family M82 contains endopeptidases.|
Identifier created: MEROPS 9.4 (31 January 2011)|
Sigma factors are transcription initiation factors that allow RNA polymerase to bind to specific gene promoters. Different environmental conditions lead to activation of different sigma factors. The activity of sigma factor W from Bacillus subtilis is also controlled by an anti-sigma factor, RsiW. RsiW is a single pass type-II membrane-anchored protein with a large extracellular domain and a small cytoplasmic domain. Damage to the cell envelope causes release of the extracellular domain of RsiW by the PrsW peptidase (M82.001), followed by C-terminal trimming by C-terminal processing peptidase-1 (S41.001, Heinrich et al., 2009). This induces the RasP peptidase (M50.004) to cleave at an intramembrane site (Schoebel et al., 2004), uncovering an alanine-rich site where cleavage by the Clp peptidase (S16.001) occurs in the cytoplasm. Degradation of RsiW leads to induction of the sigma W-controlled genes.
|Active site||No known metal-binding motifs are present. It has been suggested that two conserved glutamates (Glu75 and Glu76) in the first of the extracellular loops could be important for activity (Heinrich & Wiegert, 2006) and mutagenesis of Glu95 (which is not conserved) or His175 leads to loss of RsiW cleavage (Ellermeier & Losick, 2006).|
|Activities and specificities||The PrsW peptidase inactivates the anti-sigma factor RsiW by performing the first of several cleavages (Heinrich et al., 2009).|
|Molecular structure||No tertiary structure has been solved. The PrsW peptidase is a transmembrane protein with five membrane-spanning regions and two large extracellular loops (Heinrich & Wiegert, 2006). There are distant sequences similarities between members of families M82 and M79 (Ellermeier & Losick, 2006) and the two families probably form a clan.|