uncharacterized subgroup of the VapC3-like nuclease subfamily of the PIN domain superfamily
The VapC3-like nuclease subfamily includes the Virulence associated protein C (VapC)-like PIN (PilT N terminus) domain of various Mycobacterium tuberculosis VapC toxins including VapC3, VapC11, VapC15, VapC21, VapC25, VapC28, VapC29, VapC30, VapC32, VapC33, VapC37, and VapC39. It belongs to the VapC-like family of the PIN domain nuclease superfamily. VapC is a PIN-domain ribonuclease toxin from prokaryotic VapBC toxin-antitoxin (TA) systems. VapB is a transcription factor-like protein antitoxin acting as an inhibitor. Other members of the VapC-like nuclease family include FitB toxin of the FitAB TA system, eukaryotic ribonucleases such as Smg6, ribosome assembly factor NOB1, exosome subunit Rrp44 endoribonuclease and rRNA-processing protein Fcf1. The structural properties of the PIN 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 while some others 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: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.
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