Crystal structure of glycogen synthase: homologous enzymes catalyze glycogen synthesis and degradation
AUTOR(ES)
Buschiazzo, Alejandro
FONTE
Nature Publishing Group
RESUMO
Glycogen and starch are the major readily accessible energy storage compounds in nearly all living organisms. Glycogen is a very large branched glucose homopolymer containing about 90% α-1,4-glucosidic linkages and 10% α-1,6 linkages. Its synthesis and degradation constitute central pathways in the metabolism of living cells regulating a global carbon/energy buffer compartment. Glycogen biosynthesis involves the action of several enzymes among which glycogen synthase catalyzes the synthesis of the α-1,4-glucose backbone. We now report the first crystal structure of glycogen synthase in the presence and absence of adenosine diphosphate. The overall fold and the active site architecture of the protein are remarkably similar to those of glycogen phosphorylase, indicating a common catalytic mechanism and comparable substrate-binding properties. In contrast to glycogen phosphorylase, glycogen synthase has a much wider catalytic cleft, which is predicted to undergo an important interdomain ‘closure' movement during the catalytic cycle. The structures also provide useful hints to shed light on the allosteric regulation mechanisms of yeast/mammalian glycogen synthases.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=514502Documentos Relacionados
- Glycogen synthase: a putative locus for diet-induced hyperglycemia.
- Crystal structure of Streptococcus pneumoniae acyl carrier protein synthase: an essential enzyme in bacterial fatty acid biosynthesis
- Enzymatic phosphorylation of muscle glycogen synthase: a mechanism for maintenance of metabolic homeostasis.
- Crystal structure of the macrocycle-forming thioesterase domain of the erythromycin polyketide synthase: Versatility from a unique substrate channel
- In vivo regulation of muscle glycogen synthase and the control of glycogen synthesis.