Taxonomic group: fungi / Ascomycota
(Phylum: Ascomycota)
Organ / tissue: cell wall
NCBI PubMed ID: 25495733Publication DOI: 10.1111/febs.13176Journal NLM ID: 101229646Publisher: Blackwell Publishing
Correspondence: Arroyo J <jarroyo
farm.ucm.es>; Hurtado-Guerrero R <rhurtado
bifi.es>
Institutions: Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid, IRYCIS, Madrid, Spain, Institute of Chemistry, Center for Glycomics, Department of Glycobiology, Slovak Academy of Sciences, Bratislava, Slovakia, Institute of Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Zaragoza, Spain, BIFI-IQFR (CSIC), Zaragoza, Spain, Fundacion ARAID, Zaragoza, Spain
Covalent cross-links between chitin and glucan at the yeast cell wall are created by the transglycosylase activity of redundant proteins Crh1 and Crh2, with cleavage of β-1,4 linkages of the chitin backbone and transfer of the generated molecule containing newly created reducing end onto the glucan acceptor. A three-dimensional structure of Crh1 was generated by homology modeling based on the crystal structure of bacterial 1,3-1,4-β-D-glucanase, followed by site-directed mutagenesis to obtain molecular insights into how these enzymes achieve catalysis. The residues of both proteins that are involved in their catalytic and binding activities have been characterized by measuring the ability of yeast cells expressing different versions of these proteins to transglycosylate oligosaccharides derived from β-1,3-glucan, β-1,6-glucan and chitin to the chitin at the cell wall. Within the catalytic site, residues E134 and E138 of Crh1, as well as E166 and E170 of Crh2, corresponding to the nucleophile and general acid/base, and also the auxiliary D136 and D168 of Crh1 and Crh2, respectively, are shown to be essential for catalysis. Mutations of aromatic residues F152, Y160 and W219, located within the carbohydrate-binding cleft of the Crh1 model, also affect the transglycosylase activity. Unlike Crh1, Crh2 contains a putative carbohydrate-binding module (CBM18) of unknown function. Modeling and functional analysis of site-directed mutant residues of this CBM identified essential amino acids for protein folding and stability, as well as residues that tune the catalytic activity of Crh2.
cell wall, glucan, glycoside hydrolase, chitin, transglycosylation, computer modelling, carbohydrate binding module
Structure type: structural motif or average structure
Location inside paper: p. 715, paragraph 1
Trivial name: chitin
Compound class: cell wall polysaccharide, glucan
Contained glycoepitopes: IEDB_135813,IEDB_137340,IEDB_141807,IEDB_151531,IEDB_153212,IEDB_241099,IEDB_423114,IEDB_423150,SB_74,SB_85
Comments, role: connected to β-1,3-glucan by (1-4) link
Related record ID(s): 42326, 42327
NCBI Taxonomy refs (TaxIDs): 4932Reference(s) to other database(s): GTC:G97099AY
Show glycosyltransferases
There is only one chemically distinct structure:
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