Family C55


Summary Holotypes Alignment Tree Genomes Literature

Summary for family C55

NamePeptidase family C55 (YopJ protease family)
Family type peptidaseC55.001 - YopJ protein (Yersinia pseudotuberculosis), MEROPS Accession MER0005912 (peptidase unit: 1-264)
Content of familyPeptidase family C55 contains bacterial endopeptidases with restricted specificity.
History Identifier created: MEROPS 5.4 (23 March 2001)
The existence of the clan that came to be termed CE was revealed in 1996 by the distinctive structure of the viral peptidase, adenain (C05.001) (Ding et al., 1996). Subsequently, additional families from viruses (C57, C63), bacteria (C55) and eukaryotes (C48) have been added to the clan. The peptidases tend to show specificity for substrates with Gly in P2, P1 and P1".
Catalytic typeCysteine
Active site residuesH109 E128 Q166 C172 
Active siteActive site residues His, Glu, Gln, Cys are recognised (see the Alignment). These were identified by similarity with adenain (C05.001) (Orth et al., 2000), and are required for biological activities of peptidases in the family. No in vitro activity of the recombinant proteins has been detected.
Activities and specificitiesThere has been no direct demonstration of peptidase activity of any member of family C55 as yet, but there is strong circumstantial evidence that they have activities similar to those of the sumoyl peptidases in family C48, also in clan CE. Expression of AvrXv4 (C55.006) in plants leads to a reduction in SUMO-modified proteins (Roden et al., 2004), and the study of Denecker et al. (2001) implicated YopP, the Yersinia entericolitica form of YopJ, in the cleavage of Bid protein in infected macrophages.
Molecular structureNo three-dimensional structure is yet available for family C55, but it is placed in clan CE by reference to the identity and arrangement of active site residues (see the Alignment for clan CE).
Basis of clan assignmentActive site residues for members of this family and family C5 occur in the same order in the sequence: H, D/E, Q, C.
Distribution of family Bacteria details  
Archaea -  
Protozoa -  
Fungi -  
Plants -  
Animals -  
Viruses -  
Biological functionsThe peptidases of family C55 are responsible for certain pathogenic effects of bacteria that cause diseases in animals and plants. Exposure of macrophages to lipopolysaccharide (LPS) normally leads to production of the pro-inflammatory cytokine, tumour necrosis factor alpha (TNF-alpha), but the pathogenic Yersinia bacteria inhibit the LPS-mediated production of TNF-alpha. This effect is mediated by the protein YopJ (C55.001) that is secreted by the bacterium (Palmer et al., 1998).
Other peptidases in the family are secreted by plant pathogens, and also disable the normal defensive reactions of the host. These effects can be explained in terms of activities similar to those of ubiquitinyl and sumoyl peptidases, interfering with signalling events mediated by protein-tagging (Hotson & Mudgett, 2004).
Statistics for family C55Sequences:90
Identifiers with PDB entries:0
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Peptidases and Homologues MEROPS ID Structure
YopJ proteinC55.001-
AvrA proteinC55.003-
PopP1 g.p. (Ralstonia solanacearum)C55.004-
HopZ2 proteinC55.005-
AvrXv4 (Xanthomonas sp.)C55.006-
VopA proteinC55.007-
AopP g.p. (Aeromonas salmonicida)C55.008-
HopZ1 protein (Pseudomonas syringae)C55.009-
family C55 non-peptidase homologuesnon-peptidase homologue-
family C55 unassigned peptidasesunassigned-