Family A36


Summary Holotypes Alignment Tree Genomes Literature

Summary for family A36

Family type peptidaseA36.001 - sporulation factor SpoIIGA (Bacillus subtilis), MEROPS Accession MER0001293 (peptidase unit: 148-309)
Content of familyPeptidase family A36 contains endopeptidases.
History Identifier created: MEROPS 9.5 (1 July 2011)
Sporulation in Bacillus subtilis is controlled by proteins known as sigma factors, which are transcription factors. A sigma factor is synthesized as a precursor which is subsequently activated by proteolysis. In Bacillus two cell types are produced during sporulation, with sigma factor F being activated in the forespore and sigma factor E in the mother cell (hazand et al., 1995). Sporulation factor SpoIIGA (A36.001) activates the sigma factor E precursor and sporulation does not occur in cells where the spoIVGA gene has been knocked out (Junne et al., 2011). A third sigma factor, sigma K, is also required during sporulation and is also synthesized as a precursor which is activated by SpoIVFB (M50.002).
Catalytic typeAspartic
Active site residuesD183 
Active siteSpoIIGA is assumed to be an aspartic peptidase because of the presence of an Asp-Ser/Thr-Gly motif, in which the Asp is predicted to be an active site residue. The peptidase is believed to be active as a homodimer (Imamura et al., 2008).
Activities and specificitiesA N-terminal propeptide is removed from the sigma factor E precursor (Peters & Haldenwang, 1994).
InhibitorsNo inhibitors have been described for SpoIIGA.
Molecular structureNo tertiary structure for any member of the family has been solved. Sporulation factor SpoIIGA has five transmembrane domains (Stragier et al., 1988) in the N-terminal half, whereas the peptidase domain is C-terminal.
Distribution of family Bacteria details  
Archaea -  
Protozoa -  
Fungi -  
Plants details  
Animals -  
Viruses -  
Biological functionsThe genes for SpoIIGA and pro-sigma factor E are cotranscribed (Peters & Haldenwang, 1991). The external signal protein SpoIIR, which is produced in the forespore, is required to trigger activation of the sigma factor E precursor, and it is postulated the SpoIIGA acts as a cell surface receptor for SpoIIR as well as the peptidase responsible for pro-sigma E conversion (Hofmeister et al., 1995). Binding of SpoIIR is thought to induce activation probably by inducing a conformational change allowing the C-terminal domain of SpoIIGA to dimerize (Imamura et al., 2008). SpoIIGA is then translocated to the septum that separates the forespore and other cells (Fawcett et al., 1998).
Statistics for family A36Sequences:228
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
sporulation factor SpoIIGAA36.001-
family A36 unassigned peptidasesunassigned-