5SUK

G6P bound activated state of yeast glycogen synthase 2

Summary for 5SUK

• Entry DOI: 10.2210/pdb5suk/pdb
• Descriptor: Glycogen [starch] synthase isoform 2, 6-O-phosphono-alpha-D-glucopyranose (2 entities in total)
• Functional Keywords: activated form g6p glycogen synthase wild-type, transferase
• Biological source: Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast)
• Total number of polymer chains: 4
• Total formula weight: 331045.22

Authors

Baskaran, S.,Mahalingan, K.K.,Hurley, T.D. (deposition date: 2016-08-03, release date: 2017-06-14, Last modification date: 2023-10-04)

Primary citation

Mahalingan, K.K.,Baskaran, S.,DePaoli-Roach, A.A.,Roach, P.J.,Hurley, T.D.
Redox Switch for the Inhibited State of Yeast Glycogen Synthase Mimics Regulation by Phosphorylation.
Biochemistry, 56:179-188, 2017

PubMed 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.

PubMed: 27935293
DOI: 10.1021/acs.biochem.6b00884

Experimental method

X-RAY DIFFRACTION (2.88 Å)