LabA-like PIN domain of Pseudomonas putida S16 NicB and related proteins
Curiously NicB from Pseudomonas putida S16 is described as a putative NADH-dependent hydroxylase involved in the microbial degradation of nicotine. This subfamily also includes the uncharacterized CPP15 (plasmid) protein from Campylobacter jejuni. This subfamily belongs to LabA-like PIN domain family which includes Synechococcus elongatus PCC 7942 LabA, human ZNF451, uncharacterized Bacillus subtilis YqxD and Escherichia coli YaiI, and the N-terminal domain of a well-conserved group of mainly bacterial proteins with no defined function, which contain a C-terminal LabA_like_C domain. Curiously, a gene labeled NicB from Pseudomonas putida S16, which is described as a putative NADH-dependent hydroxylase involved in the microbial degradation of nicotine also falls into the LabA-like PIN family. The PIN (PilT N terminus) domain belongs to a large nuclease superfamily. 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: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. Some members of the superfamily lack several of these key catalytic residues. In this subgroup 4 conserved catalytic residues are found.-----------------------
Jiyao W et al.(2023). "The conserved domain database in 2023.",