|Family type peptidase||A32.001 - PerP peptidase (Caulobacter sp.) (Caulobacter crescentus), MEROPS Accession MER151383 (peptidase unit: 1-172)|
|Content of family|
Identifier created: MEROPS 9.5 (1 July 2011)|
The bacterium Caulobacter crescentus alternates between sessile and motile cell cycles. Motility is associated with the 'swarmer' phenomenon, where bacterial cells act in unison rather like a multicellular organism, whereas the sessile form adheres to a surface. In the motile form each cell has pili and a flagellum, whereas in the sessile form these organelles are replaced by a stalk. Assymetric cell division results in the production of a daughter sessile cell and a daughter swarmer cell. The PodJ protein is a transmembrane factor that recruits essential proteins to the correct cell pole. In the swarmer phase, full-length PodJ (known as PodJL) recruits proteins required for pilus formation. As the cell divides, PodJ is cleaved to a truncated form known as PodJS. PodJS protein remains attached to the membrane, where it recruits components required for stalk formation as the cell moves into the sessile stage. PerP is a periplasmic protein in Caulobacter rescentus that converts PodJL to PodJS (Chen et al., 2006).
|Active site residues||D80 |
|Active site||An Asp which occurs in a conserved Asp-Thr-Gly motif is assumed to be the active site residue, and by analogy to the HIV1 retropepsin (A02.001) the peptidase is presumed to be only active as a homodimer (Chen et al., 2006).|
|Molecular structure||From the sequence, PerP is a multidomain protein, with either an N-terminal signal peptide or transmembrane region, and a C-terminal, periplasmic, aspartic peptidase domain. No tertiary structure for any member of the family has been solved, but family A32 is included in clan AA because of the Asp-Gly-Thr motif and a weak sequence relationship to the peptidase from retrotransposon Osvaldo (A02.054).|