Structural and thermodynamic insights into the novel dinucleotide‐binding protein of ABC transporter unveils its moonlighting function

Substrate (or solute)-binding proteins (SBPs) selectively bind the target ligands and deliver them to ATP-binding cassette (ABC) transport system for their translocation. Irrespective of different types ligands, SBPs are structurally conserved. A wealth structural details bound physiological basis import available; however, uptake mechanism nucleotides is still deficient. In this study, we elucidated an SBP endogenously a novel ligand, derivative uridylyl-3′-5′-phospho-guanosine (U3G); thus, named it U3G-binding protein (U3GBP). To best our knowledge, first report U3G (and dinucleotide) binding ABC system, U3GBP classified as member subcluster D-I SBPs. Thermodynamic data also suggest that can phospholipid precursor sn-glycerophosphocholine (GPC) at site other than active site. Moreover, combination mutagenic information reveals follows well-known ‘Venus Fly-trap’ dinucleotide binding. Databases Structural available in RCSB Protein Data Bank under accession number(s) 7C0F, 7C0K, 7C0L, 7C0O, 7C0R, 7C0S, 7C0T, 7C0U, 7C0V, 7C0W, 7C0X, 7C0Y, 7C0Z, 7C14, 7C15, 7C16, 7C19, 7C1B.