Structural and functional linkages between subunit interfaces in mammalian pyruvate kinase

John O. Wooll, Robert H.E. Friesen, Mark A. White, Stanley J. Watowich, Robert O. Fox, J. Ching Lee, Edmund W. Czerwinski

Research output: Contribution to journalArticle

37 Scopus citations

Abstract

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 Å. 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.

Original languageEnglish (US)
Pages (from-to)525-540
Number of pages16
JournalJournal of Molecular Biology
Volume312
Issue number3
DOIs
StatePublished - Sep 21 2001

Keywords

  • Allosterism
  • Pyruvate kinase
  • Structure
  • Subunit communication
  • X-ray crystallography

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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