5I0F: Cycloalternan-degrading Enzyme From Trueperella Pyogenes In Complex With Covalent Intermediate

Active in the aqueous cellular environment where a massive excess of water is perpetually present, enzymes that catalyze the transfer of an electrophile to a non-water nucleophile (transferases) require specific strategies to inhibit mechanistically related hydrolysis reactions. To identify principles that confer transferase versus hydrolase reaction specificity, we exploited two enzymes that use highly similar catalytic apparatuses to catalyze the transglycosylation (a transferase reaction) or hydrolysis of alpha-1,3-glucan linkages in the cyclic tetrasaccharide cycloalternan (CA). We show that substrate binding to non-catalytic domains and a conformationally stable active site promote CA transglycosylation, whereas a distinct pattern of active site conformational change is associated with CA hydrolysis. These findings defy the classic view of induced-fit conformational change and illustrate a mechanism by which a stable hydrophobic binding site can favor transferase activity and disfavor hydrolysis. Application of these principles could facilitate the rational reengineering of transferases with desired catalytic properties.
PDB ID: 5I0FDownload
MMDB ID: 145611
PDB Deposition Date: 2016/2/3
Updated in MMDB: 2016/12
Experimental Method:
x-ray diffraction
Resolution: 1.85  Å
Source Organism:
Similar Structures:
Biological Unit for 5I0F: monomeric; determined by author and by software (PISA)
Molecular Components in 5I0F
Label Count Molecule
Protein (1 molecule)
Glycoside Hydrolase Family 31
Molecule annotation
Chemicals (13 molecules)
* Click molecule labels to explore molecular sequence information.

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