5wxx

Crystal structure of Microcystis aeruginosa PCC 7806 aspartate racemase in complex with citrate

spinqualitylabelsall models 5wxx, resolution 2.35Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5wxx is a 1 chain structure with sequence from Microcystis aeruginosa PCC 7806. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.35Å Ligands: CIT, MSE Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function Q9RNB4_MICA7 Publication Abstract from PubMed L-amino acids represent the most common amino acid form, most notably as protein residues, whereas D-amino acids, despite their rare occurrence, play significant roles in many biological processes. Amino acid racemases are enzymes that catalyze the interconversion of L- and/or D-amino acids. McyF is a pyridoxal 5'-phosphate (PLP) independent amino acid racemase that produces the substrate D-aspartate for the biosynthesis of microcystin in the cyanobacterium Microcystis aeruginosa PCC7806. Here we report the crystal structures of McyF in complex with citrate, L-Asp and D-Asp at 2.35, 2.63 and 2.80A, respectively. Structural analyses indicate that McyF and homologs possess highly conserved residues involved in substrate binding and catalysis. In addition, residues Cys87 and Cys195 were clearly assigned to the key catalytic residues of "two bases" that deprotonate D-Asp and L-Asp in a reaction independent of PLP. Further site-directed mutagenesis combined with enzymatic assays revealed that Glu197 also participates in the catalytic reaction. In addition, activity assays proved that McyF could also catalyze the interconversion of L-MeAsp between D-MeAsp, the precursor of another microcystin isoform. These findings provide structural insights into the catalytic mechanism of aspartate racemase and microcystin biosynthesis. Structural insights into the catalysis and substrate specificity of cyanobacterial aspartate racemase McyF.,Cao DD, Zhang CP, Zhou K, Jiang YL, Tan XF, Xie J, Ren YM, Chen Y, Zhou CZ, Hou WT Biochem Biophys Res Commun. 2019 Jul 5;514(4):1108-1114. doi:, 10.1016/j.bbrc.2019.05.063. Epub 2019 May 14. PMID:31101340 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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