PDBsum entry: 2eex

Hydrolase

PDB-id: 2eex

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PROCHECK

Protein chain

509 a.a. *

Ligands

CE5

GOL ×2

Metal ions

_ZN

_CA

_CL

Waters ×459

* Residue conservation analysis

Tools

Clefts Calculation

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PDB id:

2eex

Name:

Hydrolase

Title:

Crystal structure of cel44a, gh family 44 endoglucanase from clostridium thermocellum

Structure:

Endoglucanase. Chain: a. Fragment: residues 1-519. Synonym: glycoside hydrolase. Engineered: yes. Mutation: yes

Source:

Clostridium thermocellum. Organism_taxid: 1515. Strain: f1. Gene: cel44a. Expressed in: escherichia coli. Expression_system_taxid: 562.

UniProt:

P71140 (P71140_CLOTM)

Seq:

Struc:

Seq:

Struc:

Seq:

Struc:

Seq:

Struc:

Seq:

Struc:

Seq:

Struc:

Seq:

1601 a.a.

Struc:

509 a.a.*

Key:	PfamA domain	PfamB domain
Secondary structure

* PDB and UniProt seqs differ at 1 residue position (black cross)

Resolution:

2.00Å

R-factor:

0.165

R-free:

0.201

Authors:

Y.Kitago,S.Karita,N.Watanabe,K.Sakka,I.Tanaka

Key ref:

Y.Kitago et al. (2007). Crystal structure of Cel44A, a glycoside hydrolase family 44 endoglucanase from Clostridium thermocellum.. J Biol Chem, 282, 35703-35711. [PubMed id: 17905739] [DOI: 10.1074/jbc.M706835200]

Date:

19-Feb-07

Release date:

18-Sep-07

Related entries:

2e4t
high resolution
2e0p
complexed with cellopentaose

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Clefts

Surface

Key reference

DOI no: 10.1074/jbc.M706835200

J Biol Chem 282:35703-35711 (2007)

PubMed id: 17905739

Crystal structure of Cel44A, a glycoside hydrolase family 44 endoglucanase from Clostridium thermocellum.

Y.Kitago, S.Karita, N.Watanabe, M.Kamiya, T.Aizawa, K.Sakka, I.Tanaka.

ABSTRACT

The crystal structure of Cel44A, which is one of the enzymatic components of the cellulosome of Clostridium thermocellum, was solved at a resolution of 0.96 A. This enzyme belongs to glycoside hydrolase family (GH family) 44. The structure reveals that Cel44A consists of a TIM-like barrel domain and a beta-sandwich domain. The wild-type and the E186Q mutant structures complexed with substrates suggest that two glutamic acid residues, Glu(186) and Glu(359), are the active residues of the enzyme. Biochemical experiments were performed to confirm this idea. The structural features indicate that GH family 44 belongs to clan GH-A and that the reaction catalyzed by Cel44A is retaining type hydrolysis. The stereochemical course of hydrolysis was confirmed by a (1)H NMR experiment using the reduced cellooligosaccharide as a substrate.