Crystal structure of Thermotoga maritima alpha-L-fucosidase. Insights into the catalytic mechanism and the molecular basis for fucosidosis.
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Sulzenbacher G, Bignon C, Nishimura T, Tarling CA, Withers SG, Henrissat B, Bourne Y
Crystal structure of Thermotoga maritima alpha-L-fucosidase. Insights into the catalytic mechanism and the molecular basis for fucosidosis.
J Biol Chem. 2004 Mar 26;279(13):13119-28. Epub 2004 Jan 8.
- PubMed ID
- 14715651 [ View in PubMed]
- Abstract
Fucosylated glycoconjugates are involved in numerous biological events, and alpha-l-fucosidases, the enzymes responsible for their processing, are therefore of crucial importance. Deficiency in alpha-l-fucosidase activity is associated with fucosidosis, a lysosomal storage disorder characterized by rapid neurodegeneration, resulting in severe mental and motor deterioration. To gain insight into alpha-l-fucosidase function at the molecular level, we have determined the crystal structure of Thermotoga maritima alpha-l-fucosidase. This enzyme assembles as a hexamer and displays a two-domain fold, composed of a catalytic (beta/alpha)(8)-like domain and a C-terminal beta-sandwich domain. The structures of an enzyme-product complex and of a covalent glycosyl-enzyme intermediate, coupled with kinetic and mutagenesis studies, allowed us to identify the catalytic nucleophile, Asp(244), and the Bronsted acid/base, Glu(266). Because T. maritima alpha-l-fucosidase occupies a unique evolutionary position, being far more closely related to the mammalian enzymes than to any other prokaryotic homolog, a structural model of the human enzyme was built to document the structural consequences of the genetic mutations associated with fucosidosis.