Structural highlights
Publication Abstract from PubMedArginine kinase (AK) is a key enzyme for energetic balance in invertebrates. Although AK is a well-studied system that provides fast energy to invertebrates using the phosphagen phospho-arginine, the structural details on the AK-arginine binary complex interaction remain unclear. Herein, we determined two crystal structures of the Pacific whiteleg shrimp (Litopenaeus vannamei) arginine kinase, one in binary complex with arginine (LvAK-Arg) and a ternary transition state analog complex (TSAC). We found that the arginine guanidinium group makes ionic contacts with Glu225, Cys271 and a network of ordered water molecules. On the zwitterionic side of the amino acid, the backbone amide nitrogens of Gly64 and Val65 coordinate the arginine carboxylate. Glu314, one of proposed acid-base catalytic residues, did not interact with arginine in the binary complex. This residue is located in the flexible loop 310-320 that covers the active site and only stabilizes in the LvAK-TSAC. This is the first binary complex crystal structure of a guanidine kinase in complex with the guanidine substrate and could give insights into the nature of the early steps of phosphagen biosynthesis. Crystal structure of shrimp arginine kinase in binary complex with arginine-a molecular view of the phosphagen precursor binding to the enzyme.,Lopez-Zavala AA, Garcia-Orozco KD, Carrasco-Miranda JS, Sugich-Miranda R, Velazquez-Contreras EF, Criscitiello MF, Brieba LG, Rudino-Pinera E, Sotelo-Mundo RR J Bioenerg Biomembr. 2013 Jul 20. PMID:23873077[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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