Family S74


Summary Holotypes Alignment Tree Genomes Structure Literature

Summary for family S74

Family type peptidaseS74.001 - Escherichia coli phage K1F endosialidase CIMCD self-cleaving protein (Enterobacteria phage K1F), MEROPS Accession MER0151384 (peptidase unit: 911-1011)
Content of familyFamily S74 contains serine endopeptidases
History Identifier created: MEROPS 9.5 (1 July 2011)
During invasion of the host, a bacteriophage has to penetrate the cell wall and endosialidases are produced to hydrolyse the polysialic acid capsule. Endosialidase NF is synthesized as a precursor which a C-terminal propeptide which acts as a chaperone (Muhlenhoff et al., 2003). This propeptide is removed by a self-cleaving mechanism (Schulz et al., 2010).
Catalytic typeSerine
Active site residuesS911 K916 
Active siteA Ser, Lys catalytic dyad has been identified from the crystal structure (Schulz et al., 2010).
Molecular structureThe tertiary structure has been solved for the endo-N-acetylneuraminidase from enterobacteria phage K1F (Schultz et al., 2010). The fold is unlike that of any other peptidase, hence the fold of the C-terminal domain of endosialidase NF is the type structure for clan SO.
Distribution of family Bacteria details  
Archaea -  
Protozoa -  
Fungi -  
Plants -  
Animals details  
Viruses details  
Biological functionsThe C-terminal domain acts as a molecular chaperone. The precursors are enclosed in tentacle-like protrusions and once the catalytic trimer consisting of a triple beta-helix structure forms, autoproteolysis releases the chaperone domains (Stummeyer et al., 2005).
Statistics for family S74Sequences:71
Identifiers with PDB entries:2
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Peptidases and Homologues MEROPS ID Structure
Escherichia coli phage K1F endosialidase CIMCD self-cleaving proteinS74.001Yes
Bacillus subtilis phage GA-1 neck appendage CIMCD self-cleaving proteinS74.002Yes
family S74 non-peptidase homologuesnon-peptidase homologue-
family S74 unassigned peptidasesunassigned-