|Family type peptidase||C70.001 - AvrRpt2 peptidase (Pseudomonas syringae), MEROPS Accession MER0027409 (peptidase unit: 72-255)|
|Content of family||Peptidase family C70 contains a putative bacterial peptidase.|
Identifier created: MEROPS 7.0 (4 April 2005)|
The plant pathogen Pseudomonas syringae secretes disease-causing factors into the host cell via its type III secretion pathway (Hotson & Mudgett, 2004). One of these factors is the protein AvrRpt2, and there is evidence that this is a cysteine peptidase (Axtell et al., 2003). When the protein enters the plant cell it is cleaved and the RIN4 protein of the host plant cell also disappears. The RIN4 protein is intimately involved in the pathogen-host interaction (Mackey et al., 2002).
|Active site residues||C122 H208 D226 |
|Active site||A modelling study led to a sequence alignment of the AvrRpt2 protein with staphopain A (C47.001) in which Cys122, His208 and Asp226 (AvrRpt2 numbering) were aligned with residues of the catalytic triad of staphopain (Axtell et al., 2003). Mutation of Cys122, His208 or Asp226 abolished the in planta processing of AvrRpt2, and mutagenesis of Cys122 or His208 abolished the ability of AvrRpt2 to mediate elimination of the host RIN4 protein. Gln115 of AvrRpt2, preceding Cys122, appears to be located appropriately to function similarly to Gln152 in papain (C01.001).|
|Activities and specificities||There is evidence that endopeptidase activity of AvrRpt2 is responsible for its own autolytic cleavage at Gly71Gly72 and also for the elimination of the host RIN4 protein (Axtell et al., 2003; Axtell et al., 2003). The sites of cleavage in RIN4 match that in the peptidase itself (Chisholm et al., 2005).|
|Molecular structure||On the basis of the order of catalytic residues and the remote similarity to staphopain A (C47.001), AvrRpt2 is assigned to clan CA.|