Catalytic role of conserved HQGE motif in the CE6 carbohydrate esterase family.
An acetylxylan esterase (R.44), belonging to the carbohydrate esterase family 6 (CE6), retrieved from bovine rumen metagenome was analyzed. Molecular modelling and site-directed mutagenesis indicated that the enzyme possesses a catalytic triad formed by Ser(14), His(231) and Glu(152). The catalytic Ser and His have been identified in highly conserved sequences GQSX and DXXH in the CE6 family, respectively, and the active-site glutamate was part of a highly conserved sequence HQGE. This motif is situated near to the so-called Block III in the CE6 family and its role in catalysis has not been identified so far.
López-Cortés
Nieves
N
Institute of Catalysis, CSIC, Cantoblanco, 28049 Madrid, Spain.
Reyes-Duarte
Dolores
D
Beloqui
Ana
A
Polaina
Julio
J
Ghazi
Iraj
I
Golyshina
Olga V
OV
Ballesteros
Antonio
A
Golyshin
Peter N
PN
Ferrer
Manuel
M
D017398:Alternative Splicing / Q000235:genetics; D020816:Amino Acid Motifs; D000818:Animals; D001224:Aspartic Acid / Q000235:genetics / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002384:Catalysis; D002417:Cattle; D017124:Conserved Sequence; D004950:Esterases / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D018698:Glutamic Acid / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity