4TF4

ENDO/EXOCELLULASE:CELLOPENTAOSE FROM THERMOMONOSPORA

Summary for 4TF4

• Entry DOI: 10.2210/pdb4tf4/pdb
• Related PRD ID: PRD_900005
• Descriptor: T. FUSCA ENDO/EXO-CELLULASE E4 CATALYTIC DOMAIN AND CELLULOSE-BINDING DOMAIN, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-alpha-D-glucopyranose, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose, ... (5 entities in total)
• Functional Keywords: glycosyl hydrolase, cellopentaose, enzyme:product complex, alpha/alpha barrel
• Biological source: Thermobifida fusca
• Total number of polymer chains: 2
• Total formula weight: 136611.56

Authors

Sakon, J.,Wilson, D.B.,Karplus, P.A. (deposition date: 1997-05-31, release date: 1997-09-04, Last modification date: 2024-11-13)

Primary citation

Sakon, J.,Irwin, D.,Wilson, D.B.,Karplus, P.A.
Structure and mechanism of endo/exocellulase E4 from Thermomonospora fusca.
Nat.Struct.Biol., 4:810-818, 1997

PubMed Abstract: Cellulase E4 from Thermomonospora fusca is unusual in that it has characteristics of both exo- and endo-cellulases. Here we report the crystal structure of a 68K M(r) fragment of E4 (E4-68) at 1.9 A resolution. E4-68 contains both a family 9 catalytic domain, exhibiting an (alpha/alpha)6 barrel fold, and a family III cellulose binding domain, having an antiparallel beta-sandwich fold. While neither of these folds is novel, E4-68 provides the first cellulase structure having interacting catalytic and cellulose binding domains. The complexes of E4-68 with cellopentaose, cellotriose and cellobiose reveal conformational changes associated with ligand binding and allow us to propose a catalytic mechanism for family 9 enzymes. We also provide evidence that E4 has two novel characteristics: first it combines exo- and endo-activities and second, when it functions as an exo-cellulase, it cleaves off cellotetraose units.

PubMed: 9334746
DOI: 10.1038/nsb1097-810

Experimental method

X-RAY DIFFRACTION (2 Å)