title: Crystal structure of shrimp arginine kinase in binary complex with arginine-a molecular view of the phosphagen precursor binding to the enzyme.
abstract: Arginine 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.
authors.affiliation: Centro de Investigación en Alimentación y Desarrollo, A.C. (CIAD). Carretera a Ejido La Victoria Km 0.6, Apartado Postal 1735, Hermosillo, Sonora, 83304, Mexico.
authors.forename: Alonso A
authors.initials: AA
authors.lastname: López-Zavala
authors.forename: Karina D
authors.initials: KD
authors.lastname: García-Orozco
authors.forename: Jesús S
authors.initials: JS
authors.lastname: Carrasco-Miranda
authors.forename: Rocio
authors.initials: R
authors.lastname: Sugich-Miranda
authors.forename: Enrique F
authors.initials: EF
authors.lastname: Velázquez-Contreras
authors.forename: Michael F
authors.initials: MF
authors.lastname: Criscitiello
authors.forename: Luis G
authors.initials: LG
authors.lastname: Brieba
authors.forename: Enrique
authors.initials: E
authors.lastname: Rudiño-Piñera
authors.forename: Rogerio R
authors.initials: RR
authors.lastname: Sotelo-Mundo
mesh_terms: D000818:Animals; D001120:Arginine / Q000737:chemistry* / Q000378:metabolism; D001122:Arginine Kinase / Q000737:chemistry* / Q000378:metabolism; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D033561:Penaeidae / Q000201:enzymology*; D011487:Protein Conformation; D013379:Substrate Specificity
chemical_list: D001120:Arginine; D001122:Arginine Kinase