1a49
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BIS MG-ATP-K-OXALATE COMPLEX OF PYRUVATE KINASE
OverviewOverview
Pyruvate kinase from rabbit muscle has been cocrystallized as a complex, with MgIIATP, oxalate, Mg2+, and either K+ or Na+. Crystals with either, Na+ or K+ belong to the space group P2(1)2(1)2(1), and the asymmetric, units contain two tetramers. The structures were solved by molecular, replacement and refined to 2.1 (K+) and 2.35 A (Na+) resolution. The, structures of the Na+ and K+ complexes are virtually isomorphous. Each of, the eight subunits within the asymmetric unit contains MgIIoxalate as a, bidentate complex linked to the protein through coordination of Mg2+ to, the carboxylates of Glu 271 and Asp 295. Six of the subunits also contain, an alpha,beta,gamma-tridentate complex of MgIIATP, and the active-site, cleft, located between domains A and B, is closed in these subunits. In, the remaining two subunits MgIIATP is missing, and the active-site cleft, is open. Closure of the active-site cleft in the fully liganded subunits, includes a rotation of 41 degrees of the B domain relative to the A, domain. alpha-Carbons of residues in the B domain undergo movements of up, to 17.8 A (Lys 124) in the cleft closure. Lys 206, Arg 119, and Asp 177, from the B domain move several angstroms from their positions in the open, conformation to contact the MgIIATP complex in the active site. The, gamma-phosphate of ATP coordinates to both magnesium ions and to the, monovalent cation, K+ or Na+. A Mg2+-coordinated oxygen from the, MgIIoxalate complex lies 3.0 A from Pgamma of ATP, and this oxygen is, positioned for an in-line attack on the phosphorus. The side chains of Lys, 269 and Arg 119 are positioned to provide leaving-group activation in the, forward and reverse directions. There is no obvious candidate for the, acid/base catalyst near the 2-si face of the prospective enolate of the, normal substrate. A functional group linked through solvent and side-chain, hydroxyls may function in a proton relay.
About this StructureAbout this Structure
1A49 is a Single protein structure of sequence from Oryctolagus cuniculus with K, OXL, MG and ATP as ligands. Active as Pyruvate kinase, with EC number 2.7.1.40 Full crystallographic information is available from OCA.
ReferenceReference
Structure of the bis(Mg2+)-ATP-oxalate complex of the rabbit muscle pyruvate kinase at 2.1 A resolution: ATP binding over a barrel., Larsen TM, Benning MM, Rayment I, Reed GH, Biochemistry. 1998 May 5;37(18):6247-55. PMID:9572839
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