Gene Ontology annotation through association of InterPro records with GO terms
Combined Automated Annotation using Multiple IEA Methods
UniProtKB entry A0A0H2M992 (A0A0H2M992_VARPD): PqqA binding protein
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A0A0H2M992 (VPARA_00930, pqqD) is a 98-residue PqqD-family protein (HAMAP MF_00655, InterPro IPR008792, InterPro IPR022479, NCBIfam TIGR03859) that binds the precursor peptide PqqA and presents it to PqqE in the PQQ biosynthetic pathway.
"CC -!- FUNCTION: Functions as a PqqA binding protein and presents PqqA to
CC PqqE, in the pyrroloquinoline quinone (PQQ) biosynthetic pathway.
CC {ECO:0000256|HAMAP-Rule:MF_00655}."
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Monomeric PqqD physically interacts with PqqE.
"CC -!- SUBUNIT: Monomer. Interacts with PqqE. {ECO:0000256|ARBA:ARBA00011741,
CC ECO:0000256|HAMAP-Rule:MF_00655}."
PqqD is a novel peptide chaperone that forms a ternary complex with the radical S-adenosylmethionine protein PqqE in the pyrroloquinoline quinone biosynthetic pathway.
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Surface plasmon resonance, isothermal titration calorimetry, and native mass spectrometry demonstrate that PqqD is a cofactor-less peptide chaperone that binds the precursor peptide PqqA tightly (Kd ~ 200 nM) and forms a 1:1:1 ternary PqqA-PqqD-PqqE complex.
"Moreover, using SPR and isothermal calorimetry techniques, we establish for the first time that MePqqD binds MePqqA tightly (KD ∼200 nm). The formation of a ternary MePqqA-D-E complex was captured by native mass spectrometry and the KD for the MePqqAD-MePqqE interaction was found to be ∼5 μm."
Demonstration That the Radical S-Adenosylmethionine (SAM) Enzyme PqqE Catalyzes de Novo Carbon-Carbon Cross-linking within a Peptide Substrate PqqA in the Presence of the Peptide Chaperone PqqD.
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Demonstrates that PqqD is strictly required for PqqE-catalyzed radical SAM carbon-carbon cross-linking between the glutamate and tyrosine side chains of PqqA.
"These results indicate that PqqE, in conjunction with PqqD, carries out the first step in PQQ biosynthesis"
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Confirms that PqqD binds tightly to PqqA and enters into a catalytically productive ternary complex with PqqE.
"PqqD was shown to bind tightly to PqqA and to enter into a ternary complex with PqqE"
Biogenesis of the peptide-derived redox cofactor pyrroloquinoline quinone.
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Reviews structural and biophysical evidence that PqqD is a small, cofactor-less monomeric peptide recognition protein (RRE) that binds PqqA and guides its Glu and Tyr residues into the PqqE active site.
"The missing factor has turned out to be PqqD, a small, cofactor-less protein that primarily exists as a free protein (and occasionally as a C-terminal fusion protein of PqqC or an N-terminal fusion of PqqE) (Figure 1D).[12]"