1f3x
S402P MUTANT OF RABBIT MUSCLE PYRUVATE KINASE
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OverviewOverview
Mammalian pyruvate kinase (PK) is a four-domain enzyme that is active as a, homo-tetramer. Tissue-specific isozymes of PK exhibit distinct levels of, allosteric regulation. PK expressed in muscle tissue (M1-PK) shows, hyperbolic steady-state kinetics, whereas PK expressed in kidney tissue, (M2-PK) displays sigmoidal kinetics. Rabbit M1 and M2-PK are isozymes, whose sequences differ in only 22 out of 530 residues per subunit, and, these changes are localized in an inter-subunit interface. Previous, studies have shown that a single amino acid mutation to M1-PK at either, the Y (S402P) or Z (T340 M) subunit interface can confer a level of, allosteric regulation that is intermediate to M1-PK and M2-PK. In an, effort to elucidate the roles of the inter-subunit interaction in signal, transmission and the functional/structural connectivity between these, interfaces, the S402P mutant of M1-PK was crystallized and its structure, resolved to 2.8 A. Although the overall S402P M1-PK structure is nearly, identical with the wild-type structure within experimental error, significant differences in the conformation of the backbone are found at, the site of mutation along the Y interface. In addition, there is a, significant change along the Z interface, namely, a loss of an, inter-subunit salt-bridge between Asp177 of domain B and Arg341 of domain, A of the opposing subunit. Concurrent with the loss of the salt-bridge is, an increase in the degree of rotational flexibility of domain B that, constitutes the active site. Comparison of previous PK structures shows a, correlation between an increase in this domain movement with the loss of, the Asp177: Arg341 salt-bridge. These results identify the structural, linkages between the Y and Z interfaces in regulating the interconversion, of conformational states of rabbit M1-PK.
About this StructureAbout this Structure
1F3X is a Single protein structure of sequence from Oryctolagus cuniculus with K, MN and PYR as ligands. Active as Pyruvate kinase, with EC number 2.7.1.40 Full crystallographic information is available from OCA.
ReferenceReference
Structural and functional linkages between subunit interfaces in mammalian pyruvate kinase., Wooll JO, Friesen RH, White MA, Watowich SJ, Fox RO, Lee JC, Czerwinski EW, J Mol Biol. 2001 Sep 21;312(3):525-40. PMID:11563914
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