Curatorial Notes for `pstB` (`A0A0D0L7E0`, `VPARA_10450`) in Variovorax paradoxus TBEA6

1. Gene & Protein Identity

UniProt Accession: A0A0D0L7E0 (A0A0D0L7E0_VARPD)
Gene Symbol: pstB
Locus Tag / EMBL CDS: VPARA_10450 / KLN58033.1 on contig JZWI01000005 (RefSeq:WP_021007056.1)
Protein Length: 259 aa (29,009 Da); ABC transporter nucleotide-binding domain at residues 13–254 (PROSITE:PS50893 ABC_TRANSPORTER_2, Pfam:PF00005 ABC_tran, CDD:cd03260 ABC_PstB_phosphate_transporter).
Specific Family & Active-Site Conservation:
InterPro:IPR005670 (PstB-like), NCBIfam:TIGR00972 (3a0107s01c2), PANTHER:PTHR43423:SF3 (PHOSPHATE IMPORT ATP-BINDING PROTEIN PSTB).
Conserves the Walker A P-loop ATP-binding motif at residues 45–52 (45-GPSGCGKS-52, FT BINDING 45..52 /ligand="ATP") containing Gly50 and Lys51 (corresponding to E. coli PstB Gly48 and Lys49, whose mutation abolishes Pst phosphate transport and causes constitutive alkaline phosphatase derepression in PMID:2646285), the ABC signature motif 156-LSGGQQQRLCIAR-168 (PROSITE:PS00211), the Walker B catalytic glutamate Glu181 (in 176-VLLLDEPCSALD-187), and the H-loop switch histidine His212.

Encoded immediately between phoU (VPARA_10440, KLN58032.1) and pstA (VPARA_10460, KLN58034.1) within the phoR1-phoB1-phoU-pstB-pstA-pstC-pstS-ppx (VPARA_10420–VPARA_10490) phosphate regulon gene cluster.

PMID:2646285 (Cox, Webb & Rosenberg 1989 J Bacteriol): Site-directed mutagenesis of E. coli pstB (Gly48Ile, Lys49Gln) abolishes Pst phosphate transport and derepresses the Pho regulon.
PMID:24563032 (Gardner et al. 2014 J Bacteriol): Demonstrates by bacterial two-hybrid and affinity co-elution that PstB directly interacts with PhoU at the cytoplasmic face of the inner membrane to transduce the PstSCAB conformational state to PhoR.
PMID:3881386 (Surin et al. 1985 J Bacteriol): Sequence and organization of pstB in the phoS-pstC-pstA-pstB-phoU operon.

Following ECOLI/pstB (P0AAH0):
GO:0000166 (nucleotide binding, IEA GO_REF:0000104): TOO_GENERAL — entailed by GO:0005524 (ATP binding).
GO:0005315 (phosphate transmembrane transporter activity, IEA GO_REF:0000002, enables): MARK_AS_OVER_ANNOTATED — PstB is the cytoplasmic nucleotide-binding ATPase subunit of the PstSCAB holocomplex rather than the transmembrane pore; its contribution to GO:0015415 (ATPase-coupled phosphate ion transmembrane transporter activity) is captured in core_functions.contributes_to_molecular_function.
GO:0005524 (ATP binding, IEA GO_REF:0000120): KEEP_AS_NON_CORE — prerequisite cosubstrate binding for the core GO:0016887 (ATP hydrolysis activity), matching ECOLI/pstB.
GO:0005886 (plasma membrane, IEA GO_REF:0000044): ACCEPT — peripheral inner-membrane ATPase subunit.
GO:0016020 (membrane, IEA GO_REF:0000002): TOO_GENERAL — entailed by GO:0005886.
GO:0016887 (ATP hydrolysis activity, IEA GO_REF:0000002): ACCEPT — core molecular function of the PstB motor subunit.
GO:0035435 (phosphate ion transmembrane transport, IEA GO_REF:0000002): ACCEPT — core biological process energized by PstB.
GO:0055052 (ATP-binding cassette (ABC) transporter complex, substrate-binding subunit-containing, IC from file:VARPD/pstB/pstB-uniprot.txt): NEW — matching ECOLI/pstB.