|Family type peptidase||G02.001 - pre-neck appendage protein (Bacillus phage phi29) (bacteriophage phi-29), MEROPS Accession MER0151381 (peptidase unit: 692-854)|
|Content of family||Peptidase family G2 contains self-cleaving endopeptidases.|
Identifier created: MEROPS 9.5 (1 July 2011)|
In bacteriophage phi29 there are 12 appendages attached to the neck region that are important for host cell recognition and entry. Neck-appendage proteins from Bacillus phages, tail spike proteins from coliphages and K5 lyases are all homotrimers. Prior to trimerization, each subunit is autolytically processed to release its C-terminal domain (Schwarzer et al., 2007). The C-terminal domain acts as chaperone, assisting in the folding and assembly of the phage proteins.
|Active site residues||D692 E695 |
|Active site||In the self-processing of the tail spike protein of bacteriophage phi29, Glu695 from one chain is thought to activate a water molecule, which attacks the peptide bond Trp690+Ser on another chain (Schulz & Ficner, 2011). Self-cleavage is thus in trans.|
|Molecular structure||The tertiary structures of bacteriophage phi29 neck appendage protein before and after processing have been solved (Xiang et al., 2009). The fold is unique and is thus the type example for clan GB.|