PA5082

Gene Description

PA5082 (DguC) is a periplasmic solute-binding protein of the SBP_bac_3 family in Pseudomonas aeruginosa, encoded as the last gene of the D-glutamate-inducible dguABC operon together with the FAD-dependent D-amino acid dehydrogenase DguA and the RidA-family protein DguB. It has an N-terminal signal peptide and belongs to the glutamate/aspartate binding protein subfamily. A dguC lesion slightly impairs growth on D-glutamate, suggesting a minor role in D-glutamate uptake, while the AatJMQP transporter is the main route. Its ligand has not been determined experimentally.

Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0006865 amino acid transport	IBA GO_REF:0000033	TOO GENERAL	Summary: Correct for this SBP_bac_3 amino acid binding protein clade, and entailed by the accepted D-amino acid transport row. Reason: The node is grounded by E. coli GltI (IDA L-glutamate transmembrane transport), and Q9HUA1 in its own WITH/FROM marks its PseudoCAP seed, which is expected. D-amino acid transport (GO:0042940), accepted on the IMP row, is an is_a child of this term. Node-level assessment is in the PA1342 notes.
GO:0030288 outer membrane-bounded periplasmic space	IBA GO_REF:0000033	ACCEPT	Summary: Periplasmic binding protein with a predicted signal peptide. Reason: Seeded by E. coli GltI (periplasm by IDA); PA5082 has a SignalP signal peptide and the SBP_bac_3 fold. Supporting Evidence: file:PSEAE/PA5082/PA5082-uniprot.txt SIGNAL 1..22 /evidence="ECO:0000256\|SAM:SignalP" PMID:25082951 dguC encoding a periplasmic solute binding protein
GO:0042597 periplasmic space	IEA GO_REF:0000044	TOO GENERAL	Summary: True but entailed by the accepted outer membrane-bounded periplasmic space. Reason: Outer membrane-bounded periplasmic space (GO:0030288), accepted on the IBA row, is an is_a child of this term.
GO:0042940 D-amino acid transport	IMP PMID:25082951 Functional characterization of the dguRABC locus for D-Glu a...	ACCEPT	Summary: He et al. 2014 - a dguC lesion slightly impairs growth on D-Glu; dguC is in the D-Glu-induced dguABC operon. Reason: The phenotype is mild and indirect (growth, not uptake), but it is reported for this gene, and a periplasmic binding protein encoded with a D-amino acid dehydrogenase in a D-Glu-induced operon has no evident role in D-Glu use other than substrate capture for transport. GO has no D-glutamate transport term. Accepted as the gene's core process, with the caveat that the AatJMQP transporter is the main D-Glu route and the DguC ligand is unmeasured. Supporting Evidence: PMID:25082951 Whilst a lesion in dguC encoding a periplasmic solute binding protein only affected growth on D-Glu slightly PMID:25082951 the divergent dguR-dguABC (D-Glu utilization) gene cluster was shown to participate in D-Glu and D-Gln catabolism and regulation

Core Functions

Periplasmic solute-binding protein of the D-glutamate utilisation operon, with a minor role in D-glutamate uptake; ligand not yet measured.

Directly Involved In:

D-amino acid transport

Cellular Locations:

outer membrane-bounded periplasmic space

Supporting Evidence:

PMID:25082951
Whilst a lesion in dguC encoding a periplasmic solute binding protein only affected growth on D-Glu slightly

References

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Suggested Experiments

Experiment: Thermal shift and ITC ligand screening of purified DguC with D- and L-glutamate, D-glutamine and related compounds, and D-Glu uptake assays in dguC, aatJ and double mutants.

Knowledge Gaps

What is not known — curated, literature-grounded statements of the open unknowns (the inverse of core functions).

Gap: The ligand of DguC is unknown. Its subfamily binds L-Glu/L-Asp, but its operon is induced by D-Glu; whether it binds D-Glu, D-Gln or another compound, and which permease it partners with (dgu has no permease genes), has not been tested.

BIOLOGY MF_DARK