Structure of the endoglucanase I from Fusarium oxysporum: Native, cellobiose, and 3,4-epoxybutyl beta-D-cellobioside-inhibited forms, at 2.3 angstrom resolution

TY - JOUR

T1 - Structure of the endoglucanase I from Fusarium oxysporum: Native, cellobiose, and 3,4-epoxybutyl beta-D-cellobioside-inhibited forms, at 2.3 angstrom resolution

AU - Sulzenbacher, G

AU - Schulein, M

AU - Davies, G J

PY - 1997/5/13

Y1 - 1997/5/13

N2 - The mechanisms involved in the enzymatic degradation of cellulose are of great ecological and commercial importance. The breakdown of cellulose by fungal species is performed by a consortium of free enzymes, known as cellobiohydrolases and endoglucanases, which are found in many of the 57 glycosyl hydrolase families. The structure of the endoglucanase I (EG I), found in glycosyl hydrolase family 7, from the thermophilic fungus Fusarium oxysporum has been solved at 2.3 Angstrom resolution. In addition to the native enzyme, structures have also been determined with both the affinity label, 3,4-epoxybutyl beta-D-cellobioside, and the reaction product cellobiose. The affinity label is covalently bound, as expected, to the catalytic nucleophile, Glu197, with clear evidence for binding of both the R and S stereoisomers. Cellobiose is found bound to the -2 and -1 subsites of the enzyme. In marked contrast to the structure of EG I with a nonhydrolyzable thiosaccharide analog, which spanned the -2, -1, and +1 subsites and which had a skew-boat conformation for the -1 subsite sugar [Sulzenbacher, G., et al. (1996) Biochemistry 35, 15280-15287], the cellobiose complex shows no pyranoside ring distortion in the -1 subsite, implying that strain is induced primarily by the additional +1 subsite interactions and that the product is found, as expected, in its unstrained conformation.

AB - The mechanisms involved in the enzymatic degradation of cellulose are of great ecological and commercial importance. The breakdown of cellulose by fungal species is performed by a consortium of free enzymes, known as cellobiohydrolases and endoglucanases, which are found in many of the 57 glycosyl hydrolase families. The structure of the endoglucanase I (EG I), found in glycosyl hydrolase family 7, from the thermophilic fungus Fusarium oxysporum has been solved at 2.3 Angstrom resolution. In addition to the native enzyme, structures have also been determined with both the affinity label, 3,4-epoxybutyl beta-D-cellobioside, and the reaction product cellobiose. The affinity label is covalently bound, as expected, to the catalytic nucleophile, Glu197, with clear evidence for binding of both the R and S stereoisomers. Cellobiose is found bound to the -2 and -1 subsites of the enzyme. In marked contrast to the structure of EG I with a nonhydrolyzable thiosaccharide analog, which spanned the -2, -1, and +1 subsites and which had a skew-boat conformation for the -1 subsite sugar [Sulzenbacher, G., et al. (1996) Biochemistry 35, 15280-15287], the cellobiose complex shows no pyranoside ring distortion in the -1 subsite, implying that strain is induced primarily by the additional +1 subsite interactions and that the product is found, as expected, in its unstrained conformation.

KW - ACID-SEQUENCE SIMILARITIES

KW - SITE-DIRECTED INHIBITORS

KW - TRICHODERMA-REESEI

KW - CRYSTAL-STRUCTURE

KW - GLYCOSYL HYDROLASES

KW - 3-DIMENSIONAL STRUCTURE

KW - CONCANAVALIN-A

KW - MECHANISMS

KW - LYSOZYME

KW - HYDROLYSIS

M3 - Article

SN - 0006-2960

VL - 36

SP - 5902

EP - 5911

JO - Biochemistry

JF - Biochemistry

IS - 19

ER -