Family N5


Summary Holotypes Alignment Tree Genomes Structure Literature

Summary for family N5

Family type peptidaseN05.001 - picobirnavirus self-cleaving protein (Human picobirnavirus), MEROPS Accession MER0202949 (peptidase unit: 1-552)
Content of familyFamily N5 includes self-cleaving endopeptidases
History Identifier created: MEROPS 9.3 (7 September 2010)
Picobirnaviruses are double-stranded RNA viruses. The virus particle is organized around a central icosahedral core capsid consisting of 120 identical subunits (Duquerroy et al., 2009). Each subunit undergoes an autoproteolytic cleavage, releasing a peptide that remains in the capsid associated with the RNA. Autoproteolytic cleavages of asparaginyl bonds are known also for capsid and coat proteins from nodaviruses (N1), tetraviruses (N2), reoviruses (N7) and picornaviruses (N8).
Catalytic typeAsparagine
Active site residuesN45 
Active siteCleavage occurs at Asn45, and this is assumed to be the nucleophile. In the nodavirus and tetravirus coat protein an active site dimer exists, in which the other component is an aspartate or glutamate. No equivalent residue in the picobirnavirus has been identified.
Activities and specificitiesThe only peptidase activity is release of an N-terminal 44-residue peptide from the N-terminus of the coat protein.
Molecular structureThe tertiary structure of the cleaved rabbit picobirnavirus coat protein (N05.001) has been solved, the structure is unrelated to that of any other peptidase and the rabbit picobirnavirus coat protein is the type structure for clan NE. The The mature N-terminus is a beta-hairpin more than 20 angstroms distant from the globular domain that comprises the rest of the molecule. In the crystal structure the N-terminal beta-hairpin of one monomer is embedded within the second monomer of the dimer. The released peptide is not visible in the solved tertiary structure but remains within the viral capsid associated with the RNA (Duquerroy et al., 2009).
Distribution of family Bacteria -  
Archaea -  
Protozoa -  
Fungi -  
Plants -  
Animals -  
Viruses details  
Biological functionsPicobirnavirus causes diarrhoea and gastroenteritis in human (Duquerroy et al., 2009).
Statistics for family N5Sequences:6
Identifiers with PDB entries:1
Downloadable files Sequence library (FastA format)
Sequence alignment (FastA format)
Phylogenetic tree (Newick format)
Peptidases and Homologues MEROPS ID Structure
picobirnavirus self-cleaving proteinN05.001-
family N5 unassigned peptide lyasesunassignedYes