PMID: 22105902
Fujimoto Z, Kimura K
Crystal structure of bacteriophage varphiNIT1 zinc peptidase PghP that hydrolyzes gamma-glutamyl linkage of bacterial poly-gamma-glutamate.
Proteins. 2012 Mar;80(3):722-32. doi: 10.1002/prot.23229. Epub 2011 Nov 22.
Poly-gamma-glutamate hydrolase P (PghP) of Bacillus subtilis bacteriophage PhiNIT1 hydrolyzes the gamma-glutamyl peptide linkage of extracellular poly-gamma-glutamate produced by bacilli, which facilitates infection and propagation of phage progenies. Crystal structure of PghP was determined at a resolution of 1.9 A. Structure of PghP was elucidated as a globular protein with an open alpha/beta mixed core structure and a seven-stranded parallel/anti-parallel beta-sheet. The beta-sheet contained a core four-stranded parallel beta-sheet. A zinc-binding motif, His-Glu-His, was identified at the C-terminal end of the beta-sheet. Structure analysis demonstrated that PghP, which had not been previously classified into any peptidase/protease family due to lack of amino acid sequence similarity with known enzymes, had a catalytic center containing a zinc ion and an overall topology resembling mammalian carboxypeptidase A and related enzymes. Structural comparisons indicated important amino acid residues of PghP for catalysis and recognition of the gamma-peptide bond of poly-gamma-glutamate, which was confirmed by site-directed mutagenesis of PghP. Proteins 2011. (c) 2012 Wiley Periodicals, Inc.