2g29 | pdb_00002g29

crystal structure of the periplasmic nitrate-binding protein NrtA from Synechocystis PCC 6803

spinqualitylabelsall models 2g29, resolution 1.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2g29 is a 1 chain structure with sequence from Cyanobacterium synechocystis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: NO3 Gene: nrtA (Cyanobacterium synechocystis) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum Function [NRTA_SYNY3] Essential component of the nitrate-transporting system. May be the substrate-binding protein (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Cyanobacteria, blue-green algae, are the most abundant autotrophs in aquatic environments and form the base of all aquatic food chains by fixing carbon and nitrogen into cellular biomass. The single most important nutrient for photosynthesis and growth is nitrate, which is severely limiting in many aquatic environments particularly the open ocean. It is therefore not surprising that NrtA, the solute-binding component of the high-affinity nitrate ABC transporter, is the single-most abundant protein in the plasma membrane of these bacteria. Here, we describe the structure of a nitrate-specific receptor, NrtA from Synechocystis sp. PCC 6803, complexed with nitrate and determined to a resolution of 1.5 A. NrtA is significantly larger than other oxyanion-binding proteins, representing a previously uncharacterized class of transport proteins. From sequence alignments, the only other solute-binding protein in this class is CmpA, a bicarbonate-binding protein. Therefore, these organisms created a solute-binding protein for two of the most important nutrients: inorganic nitrogen and carbon. The electrostatic charge distribution of NrtA appears to force the protein off the membrane while the flexible tether facilitates the delivery of nitrate to the membrane pore. The structure not only details the determinants for nitrate selectivity in NrtA but also the bicarbonate specificity in CmpA. Nitrate and bicarbonate transport are regulated by the cytoplasmic proteins NrtC and CmpC, respectively. Interestingly, the residues lining the ligand binding pockets suggest that they both bind nitrate. This implies that the nitrogen and carbon uptake pathways are synchronized by intracellular nitrate and nitrite. Atomic structure of a nitrate-binding protein crucial for photosynthetic productivity.,Koropatkin NM, Pakrasi HB, Smith TJ Proc Natl Acad Sci U S A. 2006 Jun 27;103(26):9820-5. Epub 2006 Jun 15. PMID:16777960 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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