Regulation of Yeast Pyruvate Kinase by Ultrasensitive Allostery Independent of Phosphorylation

Yi Fan Xu, Xin Zhao, David S. Glass, Farnaz Absalan, David H. Perlman, James R. Broach, Joshua D. Rabinowitz

Research output: Contribution to journalArticle

43 Scopus citations

Abstract

Allostery and covalent modification are major means of fast-acting metabolic regulation. Their relative roles in responding to environmental changes remain, however, unclear. Here we examine this issue, using as a case study the rapid decrease in pyruvate kinase flux in yeast upon glucose removal. The main pyruvate kinase isozyme (Cdc19) is phosphorylated in response to environmental cues. It also exhibits positively cooperative (ultrasensitive) allosteric activation by fructose-1,6-bisphosphate (FBP). Glucose removal causes accumulation of Cdc19's substrate, phosphoenolpyruvate. This response is retained in strains with altered protein-kinase-A or AMP-activated-protein-kinase activity or with CDC19 carrying mutated phosphorylation sites. In contrast, yeast engineered with a CDC19 point mutation that ablates FBP-based regulation fail to accumulate phosphoenolpyruvate. They also fail to grow on ethanol and slowly resume growth upon glucose upshift. Thus, while yeast pyruvate kinase is covalently modified in response to glucose availability, its activity is controlled almost exclusively by ultrasensitive allostery.

Original languageEnglish (US)
Pages (from-to)52-62
Number of pages11
JournalMolecular Cell
Volume48
Issue number1
DOIs
StatePublished - Oct 12 2012

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Cell Biology

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