VapC-like PIN domain of Sll0205 protein and homologs.
Virulence associated protein C (VapC)-like PIN (PilT N terminus) domain of the Synechocystis sp. (strain PCC 6803) Sll0205 protein and other uncharacterized homologs are included in this subfamily. They are similar to the PIN domains of the Mycobacterium tuberculosis VapC and Neisseria gonorrhoeae FitB toxins of the prokaryotic toxin/antitoxin operons, VapBC and FitAB, respectively, which are believed to be involved in growth inhibition by regulating translation. These toxins are nearly always co-expressed with an antitoxin, a cognate protein inhibitor, forming an inert protein complex. Disassociation of the protein complex activates the ribonuclease activity of the toxin by an, as yet undefined mechanism. The PIN domain belongs to a large nuclease superfamily. The structural properties of the PIN (PilT N terminus) domain indicate its active center, consisting of three highly conserved catalytic residues which coordinate metal ions, in some members, additional metal coordinating residues can be found. Some members of the superfamily lack several of these key catalytic residues. The PIN active site is geometrically similar in the active center of structure-specific 5' nucleases, PIN-domain ribonucleases of eukaryotic rRNA editing proteins, and bacterial toxins of toxin-antitoxin (TA) operons.
Comment:based on structure and experimental evidence from PIN-superfamily members belonging to the FEN-like, VapC-like, PRORP-like, and LabA-like families
Comment:The PIN domain superfamily contains three highly conserved catalytic residues which coordinate metal ions; in some members, additional metal coordinating residues can be found while some others lack several of these key catalytic residues. In this subgroup 4 conserved catalytic residues are found.
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