β‐Glucosidase, β‐galactosidase, family A cellulases, family F xylanases and two barley glycanases form a superfamily of enzymes wit 8‐fold β/α architecture and with two conserved glutamates near the carboxy‐terminal ends of β‐strands four and seven

FEBS Letters

Lo Leggio, Leila¹  Pickersgill, Richard¹  Jenkins, John¹  Harris, Gillian¹ 

[1] Protein Crystallography, Department of Protein Engineering, Institute of Food Research, Reading Laboratory, Earley Gate, Whiteknights Road, Reading, RG6 2EF, UK

关键词: Superfamily;    Glycosyl hydrolase;    Family F xylanase;    8-Fold β/α-barrel;    β(1–3) and β(1–3;    1–4) glucanase;    PDB;    Brookhaven Protein Databank;    xylA;    xylanase A;    GHS;    (1–3)-β-glucanase;    GHR;    (1–3;    1–4)β-glucanase;    pNPC;    p-nitrophenyl cellobioside;    β-gal;    β-galactosidase;    s.d.m.;    site directed mutagenesis;   

DOI  :  10.1016/0014-5793(95)00252-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Comparison of the recently determined crystal structures Pseudomonas fluorescens subsp. cellulosa family F xylanase, (1–3)-β-glucanase and (1–3,1–4)-β-glucanase and the catalytic domain of E. coli β-galactosidase reveals that they belong to a superfamily of 8-fold β/α-barrels with similar amino acid residues at their active sites. In the three families that these enzymes represent, the nucleophile is a glutamate, which is located close to the carboxy-terminus of β-strand seven. In addition all three enzymes have the sequence asparagine-glutamate close to the carboxy-terminus of β-strand four. This glutamate has been identified as the acid/base in the family F xylanases and is essential for catalysis in β-galactosidase. We suggest that the equivalent residue in the barley glucanases is the acid/base. Analysis of the sequences of family 1 β-glucosidases and family 5 cellulases shows that these enzymes also belong to this superfamily which we call the superfamily.

【 授权许可】

Unknown