DB code: D00502

RLCP classification	1.30.35885.972 : Hydrolysis
CATH domain	3.20.20.80 : TIM Barrel	Catalytic domain
CATH domain	2.60.40.290 : Immunoglobulin-like
E.C.	3.2.1.4
CSA
M-CSA
MACiE

CATH domain	Related DB codes (homologues)
2.60.40.290 : Immunoglobulin-like	M00219 D00479 D00504 M00026 M00192
3.20.20.80 : TIM Barrel	S00202 S00210 S00748 S00906 S00907 S00911 S00912 S00915 M00134 M00160 D00479 S00204 S00205 S00206 S00207 S00203 S00208 S00209 S00211 S00213 S00214 M00113 T00307 D00165 D00166 D00169 D00176 D00501 D00503 D00844 D00861 D00864 M00026 M00112 M00193 M00346 T00057 T00062 T00063 T00066 T00067

Uniprot Enzyme Name
UniprotKB	Protein name	Synonyms	RefSeq	CAZy	Pfam
P54583	Endoglucanase E1	EC 3.2.1.4 Endo-1,4-beta-glucanase E1 Cellulase E1 Endocellulase E1	YP_872373.1 (Protein) NC_008578.1 (DNA/RNA sequence)	CBM2 (Carbohydrate-Binding Module Family 2) GH5 (Glycoside Hydrolase Family 5)	PF00553 (CBM_2) PF00150 (Cellulase) [Graphical View]

KEGG enzyme name
cellulase endo-1,4-beta-D-glucanase beta-1,4-glucanase beta-1,4-endoglucan hydrolase celluase A cellulosin AP endoglucanase D alkali cellulase cellulase A 3 celludextrinase 9.5 cellulase avicelase pancellase SS 1,4-(1,3 1,4)-beta-D-glucan 4-glucanohydrolase

UniprotKB: Accession Number	Entry name	Activity	Subunit	Subcellular location	Cofactor
P54583	GUN1_ACIC1	Endohydrolysis of (1->4)-beta-D-glucosidic linkages in cellulose, lichenin and cereal beta-D-glucans.

KEGG Pathways
Map code	Pathways	E.C.
MAP00500	Starch and sucrose metabolism

Compound table
	Substrates				Products		Intermediates
KEGG-id	C00760	C00001	C00478	C00551	C00760	C00551	I00120
E.C.
Compound	Cellulose	H2O	Lichenin	beta-D-Glucan	Cellulose	beta-D-Glucan	Peptidyl-Glu-cellulose
Type	polysaccharide	H2O	carbohydrate	polysaccharide	polysaccharide	polysaccharide
ChEBI		15377 15377
PubChem		22247451 962 22247451 962	439241 439241	46173706 46173706		46173706 46173706

1c0dA	Unbound		Unbound	Unbound	Unbound	Unbound	Unbound
1c0dB	Unbound		Unbound	Unbound	Unbound	Unbound	Unbound
1eceA	Analogue:GLC-GLC-GLC-GLC		Unbound	Bound:GLC-GLC-GLC-GLC	Unbound	Unbound	Unbound
1eceB	Analogue:GLC-GLC-GLC-GLC		Unbound	Bound:GLC-GLC-GLC-GLC	Unbound	Unbound	Unbound
1vrxA	Unbound		Unbound	Unbound	Unbound	Unbound	Unbound
1vrxB	Unbound		Unbound	Unbound	Unbound	Unbound	Unbound

Reference for Active-site residues
resource	references	E.C.

Active-site residues
PDB	Catalytic residues	Cofactor-binding residues	Modified residues	Main-chain involved in catalysis	Comment

1c0dA	ARG 62;ASN 161;GLU 162;HIS 238;TYR 240;GLU 282
1c0dB	ARG 62;ASN 161;GLU 162;HIS 238;TYR 240;GLU 282
1eceA	ARG 62;ASN 161;GLU 162;HIS 238;TYR 240;GLU 282
1eceB	ARG 62;ASN 161;GLU 162;HIS 238;TYR 240;GLU 282
1vrxA	ARG 62;ASN 161;GLU 162;HIS 238;TYR 240;GLU 282
1vrxB	ARG 62;ASN 161;GLU 162;HIS 238;TYR 240;GLU 282

References for Catalytic Mechanism
References	Sections	No. of steps in catalysis
[3]	p.10656-10657, Fig.9	4
[6]	Fig.3	4
[7]	Fig.1, Fig.2	4

References
[1]
Resource
Comments	X-ray crystallography (2.15 Angstroms)
Medline ID	95393242
PubMed ID	7664125
Journal	Nat Struct Biol
Year	1995
Volume	2
Pages	569-76
Authors	Dominguez R, Souchon H, Spinelli S, Dauter Z, Wilson KS, Chauvaux S, Beguin P, Alzari PM
Title	A common protein fold and similar active site in two distinct families of beta-glycanases.
Related PDB	1cec
Related UniProtKB	P07985
[2]
Resource
Comments	X-ray crystallography (1.64 Angstroms) of 27-406
Medline ID	96097400
PubMed ID	8535787
Journal	Structure
Year	1995
Volume	3
Pages	939-49
Authors	Ducros V, Czjzek M, Belaich A, Gaudin C, Fierobe HP, Belaich JP, Davies GJ, Haser R
Title	Crystal structure of the catalytic domain of a bacterial cellulase belonging to family 5.
Related PDB	1edg
Related UniProtKB	P17901
[3]
Resource
Comments	X-ray crystallography (2.4 Angstroms)
Medline ID	96346058
PubMed ID	8718854
Journal	Biochemistry
Year	1996
Volume	35
Pages	10648-60
Authors	Sakon,J. , Adney,W S. , Himmel,M E. , Thomas,S R. , Karplus,P A
Title	Crystal structure of thermostable family 5 endocellulase E1 from Acidothermus cellulolyticus in complex with cellotetraose.
Related PDB	1ece
Related UniProtKB	P54583
[4]
Resource
Comments	X-ray crystallography (2.3 Angstroms) of mutant GLN-140.
Medline ID	96192088
PubMed ID	8632467
Journal	J Mol Biol
Year	1996
Volume	257
Pages	1042-51
Authors	Dominguez R, Souchon H, Lascombe M, Alzari PM
Title	The crystal structure of a family 5 endoglucanase mutant in complexed and uncomplexed forms reveals an induced fit activation mechanism.
Related PDB	1cen 1ceo
Related UniProtKB	P07985
[5]
Resource
Comments	structure by NMR of 365-426
Medline ID	98070232
PubMed ID	9405041
Journal	Biochemistry
Year	1997
Volume	36
Pages	16074-86
Authors	Brun E, Moriaud F, Gans P, Blackledge MJ, Barras F, Marion D
Title	Solution structure of the cellulose-binding domain of the endoglucanase Z secreted by Erwinia chrysanthemi.
Related PDB
Related UniProtKB	P07103
[6]
Resource
Comments	X-ray crystallography (1.57 Angstroms) of 30-329
Medline ID	98153671
PubMed ID	9485319
Journal	Biochemistry
Year	1998
Volume	37
Pages	1926-32
Authors	Davies GJ, Dauter M, Brzozowski AM, Bjornvad ME, Andersen KV, Schulein M
Title	Structure of the Bacillus agaradherans family 5 endoglucanase at 1.6 A and its cellobiose complex at 2.0 A resolution.
Related PDB	1a3h 2a3h
Related UniProtKB	O85465
[7]
Resource
Comments	X-ray crystallography (1.64 Angstroms) of 30-329
Medline ID	98384136
PubMed ID	9718293
Journal	Biochemistry
Year	1998
Volume	37
Pages	11707-13
Authors	Davies GJ, Mackenzie L, Varrot A, Dauter M, Brzozowski AM, Schulein M, Withers SG
Title	Snapshots along an enzymatic reaction coordinate: analysis of a retaining beta-glycoside hydrolase.
Related PDB	3a3h 4a3h 5a3h 6a3h 7a3h
Related UniProtKB	O85465
[8]
Resource
Comments	X-ray crystallography (1.75/1.95/2.1 Angstroms)
Medline ID
PubMed ID	10731432
Journal	J Mol Biol
Year	2000
Volume	297
Pages	819-28
Authors	Varrot A, Schulein M, Davies GJ
Title	Insights into ligand-induced conformational change in Cel5A from Bacillus agaradhaerens revealed by a catalytically active crystal form.
Related PDB	1qhz 1qi0 1qi2
Related UniProtKB
[9]
Resource
Comments	X-ray crystallography (2.3 Angstroms) of 44-335
Medline ID	21392910
PubMed ID	11501995
Journal	J Mol Biol
Year	2001
Volume	310
Pages	1055-66
Authors	Chapon V, Czjzek M, El Hassouni M, Py B, Juy M, Barras F
Title	Type II protein secretion in gram-negative pathogenic bacteria: the study of the structure/secretion relationships of the cellulase Cel5 (formerly EGZ) from Erwinia chrysanthemi.
Related PDB
Related UniProtKB	P07103
[10]
Resource
Comments	X-ray crystallography, catalysis
Medline ID
PubMed ID	12079387
Journal	J Mol Biol
Year	2002
Volume	320
Pages	303-9
Authors	Shaw A, Bott R, Vonrhein C, Bricogne G, Power S, Day AG
Title	A novel combination of two classic catalytic schemes.
Related PDB
Related UniProtKB
[11]
Resource
Comments
Medline ID
PubMed ID	15917594
Journal	Appl Biochem Biotechnol
Year	2005
Volume	121-124
Pages	129-48
Authors	Baker JO, McCarley JR, Lovett R, Yu CH, Adney WS, Rignall TR, Vinzant TB, Decker SR, Sakon J, Himmel ME
Title	Catalytically enhanced endocellulase Cel5A from Acidothermus cellulolyticus.
Related PDB	1c0d 1vrx
Related UniProtKB

Comments
This family belongs to glycosidase family-5, which has an retaining mechanism (equatorial to equatorial conformation), and also a family of 4/7 superfamily, which has got catalytic residues at the C-terminal ends of beta-4 and beta-7 on the (alpha/beta)8 barrel fold. This enzyme is composed of the N-terminal catalytic domain and the C-terminal Cellulose-binding domain. The structure of the C-terminal domain has not been determined yet. This enzyme must have the same catalytic mechanism as that of the other TIM barrel cellulases (S00203, D00501 & D00503 in EzCatDB). According to the literature [3], Glu282 and Glu162 (of 1ece) act as a nucleophile and acid-base, respectively. The catalysis proceeds through a dissociative-type (or SN1-like) mechanism, with a formation of oxocarbonium ion in the transition state, during the glycosylation of the active site. During the glycosylation, Glu282 approaches the C1 atom of the glcose, whilst Glu162 protonates the leaving group. At the second stage, or during the deglycosylation, a water molecule can be activated by a general base, Glu162. This deglycosylation also goes through the dissociative-type reaction with an oxocarbonium ion in the transition state, in which water replaced the glycosyl leaving group in the first step. Moreover, comparing the structural data with that of xylanase (E.C. 3.2.1.8) (D00479 in EzCatDB), Tyr240 (of 1ece) might stabilize the leaving nucleophile, Glu282 in deglycosylation, whilst His238 might modulate the activity of Glu162 (see [3]). On the other hand, Tyr240 might modulate the activity of the nucleophile, according to the data of the other homologous enzyme, beta-glucosidase (E.C. 3.2.1.21) (S00205 in EzCatDB).

Comments

This family belongs to glycosidase family-5, which has an retaining mechanism (equatorial to equatorial conformation), and also a family of 4/7 superfamily, which has got catalytic residues at the C-terminal ends of beta-4 and beta-7 on the (alpha/beta)8 barrel fold.
This enzyme is composed of the N-terminal catalytic domain and the C-terminal Cellulose-binding domain. The structure of the C-terminal domain has not been determined yet.
This enzyme must have the same catalytic mechanism as that of the other TIM barrel cellulases (S00203, D00501 & D00503 in EzCatDB).
According to the literature [3], Glu282 and Glu162 (of 1ece) act as a nucleophile and acid-base, respectively. The catalysis proceeds through a dissociative-type (or SN1-like) mechanism, with a formation of oxocarbonium ion in the transition state, during the glycosylation of the active site. During the glycosylation, Glu282 approaches the C1 atom of the glcose, whilst Glu162 protonates the leaving group. At the second stage, or during the deglycosylation, a water molecule can be activated by a general base, Glu162. This deglycosylation also goes through the dissociative-type reaction with an oxocarbonium ion in the transition state, in which water replaced the glycosyl leaving group in the first step.
Moreover, comparing the structural data with that of xylanase (E.C. 3.2.1.8) (D00479 in EzCatDB), Tyr240 (of 1ece) might stabilize the leaving nucleophile, Glu282 in deglycosylation, whilst His238 might modulate the activity of Glu162 (see [3]). On the other hand, Tyr240 might modulate the activity of the nucleophile, according to the data of the other homologous enzyme, beta-glucosidase (E.C. 3.2.1.21) (S00205 in EzCatDB).

Created	Updated
2002-10-18	2012-02-14