Family N7
Summary for family N7
Family type peptidase | N07.001 - reovirus type 1 coat protein (Mammalian orthoreovirus 1), MEROPS Accession MER0191303 (peptidase unit: 2-708) |
Content of family | Family N7 includes self-cleaving endopeptidases |
History |
Identifier created: MEROPS 9.3 (7 September 2010) Reoviruses are double-stranded DNA viruses. The virus particle consists of two concentric, icosahedral protein capsids surrounding a ten segment, double-stranded RNA genome (Zhang etal, 2005). One of the capsid proteins, known as mu-1, undergoes an autoproteolytic cleavage, releasing a peptide that remains in the capsid associated with the RNA. Similar autoproteolytic cleavages are known for coat proteins from nodaviruses (family N1), tetraviruses (N2), picobirnaviruses (N5) and picornaviruses (N8). |
Catalytic type | Asparagine |
Active site residues | N42 |
Active site | Cleavage occurs at Asn42, and this is assumed to be the nucleophile. Substitution of Asn42 prevents cleavage (Odegard et al., 2004). Presumably, by analogy to other coat proteins a second residue is required to form a catalytic dyad, which is Asp in the nodavirus coat protein (N01.001) or Glu in the tetravirus coat protein (N02.001). |
Activities and specificities | The only peptidase activity is release an N-terminal 42-residue peptide from the N-terminus of the coat protein. |
Molecular structure | The mu-1 protein is myristoylated at its N-terminus. The tertiary structure of the cleaved mu-1 protein has been solved and shows a fold unrelated to that of any other peptidase (Zhang et al., 2005). The structure of the mu-1 protein is therefore the type structure for clan NC. |
Clan | NC |
Distribution of family
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Bacteria |
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Archaea |
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Protozoa |
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Fungi |
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Plants |
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Animals |
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Viruses |
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Biological functions | The peptide released by cleavage of mu-1 i s known as mu-1N. A second cleavage by an unknown, exogenous peptidase releases a peptide known as phi from the C-terminus (the cleavage site has not been determined). Both mu-1N and phi are myristoylated and associate with host erythrocyte membranes where both contribute to pore formation and ultimately to membrane penetration by virus particles (Ivanovic et al., 2008). |
Statistics for family N7 | Sequences: | 22 |
| Identifiers: | 2 |
| 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 |
reovirus type 1 coat protein | N07.001 | Yes |
aquareovirus coat protein | N07.002 | - |
Family N07 unassigned peptidases | unassigned | - |