Structural highlights
Function
GAS2_YEAST Splits internally a 1,3-beta-glucan molecule and transfers the newly generated reducing end (the donor) to the non-reducing end of another 1,3-beta-glucan molecule (the acceptor) forming a 1,3-beta linkage, resulting in the elongation of 1,3-beta-glucan chains in the cell wall. Involved in spore wall assembly.[1] [2]
Publication Abstract from PubMed
The conversion of glycoside hydrolases (GHs) into transglycosylases (TGs), i.e., from enzymes that hydrolyze carbohydrates to enzymes that synthesize them, represents a promising solution for the large-scale synthesis of complex carbohydrates for biotechnological purposes. However, the lack of knowledge about the molecular details of transglycosylation hampers the rational design of TGs. Here we present the first crystallographic structure of a natural glycosyl-enzyme intermediate (GEI) of Saccharomyces cerevisiae Gas2 in complex with an acceptor substrate and demonstrate, by means of quantum mechanics/molecular mechanics metadynamics simulations, that it is tuned for transglycosylation (DeltaG = 12 kcal/mol). The 2-OH...nucleophile interaction is found to be essential for catalysis: its removal raises the free energy barrier significantly (11 and 16 kcal/mol for glycosylation and transglycosylation, respectively) and alters the conformational itinerary of the substrate (from 4C1 --> [4E] --> 1,4B/4E to 4C1 --> [4H3] --> 4C1). Our results suggest that changes in the interactions involving the 2-position could have an impact on the transglycosylation activity of several GHs.
A Trapped Covalent Intermediate of a Glycoside Hydrolase on the Pathway to Transglycosylation. Insights from Experiments and Quantum Mechanics/Molecular Mechanics Simulations.,Raich L, Borodkin V, Fang W, Castro-Lopez J, van Aalten DM, Hurtado-Guerrero R, Rovira C J Am Chem Soc. 2016 Mar 1. PMID:26859322[3]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Ragni E, Coluccio A, Rolli E, Rodriguez-Pena JM, Colasante G, Arroyo J, Neiman AM, Popolo L. GAS2 and GAS4, a pair of developmentally regulated genes required for spore wall assembly in Saccharomyces cerevisiae. Eukaryot Cell. 2007 Feb;6(2):302-16. Epub 2006 Dec 22. PMID:17189486 doi:http://dx.doi.org/EC.00321-06
- ↑ Ragni E, Fontaine T, Gissi C, Latge JP, Popolo L. The Gas family of proteins of Saccharomyces cerevisiae: characterization and evolutionary analysis. Yeast. 2007 Apr;24(4):297-308. PMID:17397106 doi:http://dx.doi.org/10.1002/yea.1473
- ↑ Raich L, Borodkin V, Fang W, Castro-Lopez J, van Aalten DM, Hurtado-Guerrero R, Rovira C. A Trapped Covalent Intermediate of a Glycoside Hydrolase on the Pathway to Transglycosylation. Insights from Experiments and Quantum Mechanics/Molecular Mechanics Simulations. J Am Chem Soc. 2016 Mar 1. PMID:26859322 doi:http://dx.doi.org/10.1021/jacs.5b10092
