InterPro domain: IPR006286

PfpI from Pyrococcus furiosus functions as a protein deglycase that repairs methylglyoxal- and glyoxal-glycated proteins [ 1 ]. Pfpi-like proteins have been found in bacteria, archaea, in some plants and in amoebae. The structure of P. horikoshii PfpI shows an alpha/beta sandwich fold, which consists of a central beta sheet flanked by two helices and two strands on one side, and by six helices and two strands on the other side. The fold resembles that of glutamine amidotransferases (GATase) of class I, which are characterised by a conserved Cys-His-Glu active site. The catalytically essential cysteine is located at a nucleophile elbow. PfpI forms a hexameric structure and the active sites are formed at the interfaces between three pairs of monomers. Cys and His form a triad with a glutamate residue from an adjacent monomer [ 2 ].

Other proteins in this group:

• Bacillus subtilis general stress protein 18 (GSP18/yfkM) [ 3 ].
• E. coli protein yhbO. It is involved in protection against environmental stresses. It has deglycase activity, and can repair glyoxal- and methylglyoxal-glycated proteins and nucleic acids [ 4 , 5 ].

This group of proteins form part of the MEROPS peptidase family C56 (Pfp1 endopeptidase, clan PC(C)).

1. DJ-1 family Maillard deglycases prevent acrylamide formation. Biochem. Biophys. Res. Commun. 478, 1111-6
2. Crystal structure of an intracellular protease from Pyrococcus horikoshii at 2-A resolution. Proc. Natl. Acad. Sci. U.S.A. 97, 14079-84
3. Methylglyoxal resistance in Bacillus subtilis: contributions of bacillithiol-dependent and independent pathways. Mol. Microbiol. 91, 706-15
4. The DJ-1 superfamily members YhbO and YajL from Escherichia coli repair proteins from glycation by methylglyoxal and glyoxal. Biochem. Biophys. Res. Commun. 470, 282-6
5. Guanine glycation repair by DJ-1/Park7 and its bacterial homologs. Science 357, 208-211