7cxs
From Proteopedia
Crystal structure of CmnK, a L-Dap formation enzyme in capreomycin biosynthesis
Structural highlights
FunctionPublication Abstract from PubMedCapreomycin (CMN) and viomycin (VIO) are nonribosomal peptide antituberculosis antibiotics, the structures of which contain four nonproteinogenic amino acids, including l-2,3-diaminopropionic acid (l-Dap), beta-ureidodehydroalanine, l-capreomycidine, and beta-lysine. Previous bioinformatics analysis suggested that CmnB/VioB and CmnK/VioK participate in the formation of l-Dap; however, the real substrates of these enzymes are yet to be confirmed. We herein show that starting from O-phospho-l-Ser (OPS) and l-Glu precursors, CmnB catalyzes the condensation reaction to generate a metabolite intermediate N-(1-amino-1-carboxyl-2-ethyl)glutamic acid (ACEGA), which undergoes NAD(+)-dependent oxidative hydrolysis by CmnK to generate l-Dap. Furthermore, the binding site of ACEGA and the catalytic mechanism of CmnK were elucidated with the assistance of three crystal structures, including those of apo-CmnK, the NAD(+)-CmnK complex, and CmnK in an alternative conformation. The CmnK-ACEGA docking model revealed that the glutamate alpha-hydrogen points toward the nicotinamide moiety. It provides evidence that the reaction is dependent on hydride transfer to form an imine intermediate, which is subsequently hydrolyzed by a water molecule to produce l-Dap. These findings modify the original proposed pathway and provide insights into l-Dap formation in the biosynthesis of other related natural products. Characterization of Enzymes Catalyzing the Formation of the Nonproteinogenic Amino Acid l-Dap in Capreomycin Biosynthesis.,Hsu SH, Zhang S, Huang SC, Wu TK, Xu Z, Chang CY Biochemistry. 2021 Jan 12;60(1):77-84. doi: 10.1021/acs.biochem.0c00808. Epub, 2020 Dec 23. PMID:33356147[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
|