Redox Switch for the Inhibited State of Yeast Glycogen Synthase Mimics Regulation by Phosphorylation

Krishna K. Mahalingan, Sulochanadevi Baskaran, Anna De Paoli-Roach, Peter Roach, Thomas Hurley

Research output: Contribution to journalArticle

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Abstract

Glycogen synthase (GS) is the rate limiting enzyme in the synthesis of glycogen. Eukaryotic GS is negatively regulated by covalent phosphorylation and allosterically activated by glucose-6-phosphate (G-6-P). To gain structural insights into the inhibited state of the enzyme, we solved the crystal structure of yGsy2-R589A/R592A to a resolution of 3.3 Å. The double mutant has an activity ratio similar to the phosphorylated enzyme and also retains the ability to be activated by G-6-P. When compared to the 2.88 Å structure of the wild-type G-6-P activated enzyme, the crystal structure of the low-activity mutant showed that the N-terminal domain of the inhibited state is tightly held against the dimer-related interface thereby hindering acceptor access to the catalytic cleft. On the basis of these two structural observations, we developed a reversible redox regulatory feature in yeast GS by substituting cysteine residues for two highly conserved arginine residues. When oxidized, the cysteine mutant enzyme exhibits activity levels similar to the phosphorylated enzyme but cannot be activated by G-6-P. Upon reduction, the cysteine mutant enzyme regains normal activity levels and regulatory response to G-6-P activation.

Original languageEnglish (US)
Pages (from-to)179-188
Number of pages10
JournalBiochemistry
Volume56
Issue number1
DOIs
StatePublished - Jan 10 2017

Fingerprint

Glycogen Synthase
Phosphorylation
Yeast
Oxidation-Reduction
Yeasts
Switches
Glucose-6-Phosphate
Enzymes
Cysteine
Crystal structure
Regain
Enzyme activity
Glycogen
Dimers
Arginine
Chemical activation

ASJC Scopus subject areas

  • Biochemistry

Cite this

Redox Switch for the Inhibited State of Yeast Glycogen Synthase Mimics Regulation by Phosphorylation. / Mahalingan, Krishna K.; Baskaran, Sulochanadevi; De Paoli-Roach, Anna; Roach, Peter; Hurley, Thomas.

In: Biochemistry, Vol. 56, No. 1, 10.01.2017, p. 179-188.

Research output: Contribution to journalArticle

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AU - Hurley, Thomas

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