DB code: S00915

RLCP classification 1.30.36027.984 : Hydrolysis
CATH domain 3.20.20.80 : TIM Barrel Catalytic domain
E.C. 3.2.1.78
CSA
M-CSA
MACiE

CATH domain Related DB codes (homologues)
3.20.20.80 : TIM Barrel S00202 S00210 S00748 S00906 S00907 S00911 S00912 M00134 M00160 D00479 S00204 S00205 S00206 S00207 S00203 S00208 S00209 S00211 S00213 S00214 M00113 T00307 D00165 D00166 D00169 D00176 D00501 D00502 D00503 D00844 D00861 D00864 M00026 M00112 M00193 M00346 T00057 T00062 T00063 T00066 T00067

Uniprot Enzyme Name
UniprotKB Protein name Synonyms RefSeq CAZy Pfam
B3PGI1
Endo-1, 4-beta mannanase, putative, man26C
EC 3.2.1.78
YP_001980760.1 (Protein)
NC_010995.1 (DNA/RNA sequence)
GH26 (Glycoside Hydrolase Family 26)
PF02156 (Glyco_hydro_26)
[Graphical View]

KEGG enzyme name
Mannan endo-1,4-beta-mannosidase
Endo-1,4-beta-mannanase
Endo-beta-1,4-mannase
Beta-mannanase B
Beta-1, 4-mannan 4-mannanohydrolase
Endo-beta-mannanase
Beta-D-mannanase
1,4-beta-D-mannan mannanohydrolase

UniprotKB: Accession Number Entry name Activity Subunit Subcellular location Cofactor
B3PGI1 B3PGI1_CELJU

KEGG Pathways
Map code Pathways E.C.
MAP00051 Fructose and mannose metabolism

Compound table
Substrates Products Intermediates
KEGG-id C02492 C00883 C00001 C01728 L00074 C02492 C00883 I00129 I00130
E.C.
Compound 1,4-beta-D-Mannan Galactomannan H2O Mannobiose Galactomannobiose 1,4-beta-D-Mannan Galactomannan Peptidyl-Glu-D-mannobiose Peptidyl-Glu-D-galactomannobiose
Type polysaccharide polysaccharide H2O polysaccharide polysaccharide polysaccharide polysaccharide
ChEBI 27680
 27680
 		15377
 15377
 		62357
 62357
 		27680
 27680
 		27680
 27680
PubChem 439336
 439336
 		22247451
 962
 22247451
 962
 		439557
 439557
 		439336
 439336
 		439336
 439336
2vx4A00 Unbound Unbound Unbound Unbound Unbound Unbound Unbound Unbound
2vx5A00 Unbound Unbound Analogue:BMA Unbound Unbound Unbound Unbound Unbound
2vx6A00 Unbound Bound:GLA-BMA-BMA-BMA-BMA Unbound Unbound Unbound Unbound Unbound Unbound
2vx7A00 Unbound Unbound Bound:MAB Unbound Unbound Unbound Unbound Unbound

Reference for Active-site residues
resource references E.C.
Literature [2]

Active-site residues
PDB Catalytic residues Cofactor-binding residues Modified residues Main-chain involved in catalysis Comment
2vx4A00 ARG 217;HIS 220;GLU 221;TRP 226;TYR 297;GLU 338;TRP 373
2vx5A00 ARG 217;HIS 220;GLU 221;TRP 226;TYR 297;GLU 338;TRP 373
2vx6A00 ARG 217;HIS 220;GLU 221;TRP 226;TYR 297;GLU 338;TRP 373
2vx7A00 ARG 217;HIS 220;GLU 221;TRP 226;TYR 297;;TRP 373 mutant E338A

References for Catalytic Mechanism
References Sections No. of steps in catalysis
[1]
FIGURE 1b
[2]
p.31187, p.31190-31191
[3]
Scheme 3
[5]
Figure 4, p.34405-34409
[8]
Fig. 2

References
[1]
Resource
Comments
Medline ID
PubMed ID 10639071
Journal Acc Chem Res
Year 2000
Volume 33
Pages 11-8
Authors Zechel DL, Withers SG
Title Glycosidase mechanisms: anatomy of a finely tuned catalyst.
Related PDB
Related UniProtKB
[2]
Resource
Comments
Medline ID
PubMed ID 11382747
Journal J Biol Chem
Year 2001
Volume 276
Pages 31186-92
Authors Hogg D, Woo EJ, Bolam DN, McKie VA, Gilbert HJ, Pickersgill RW
Title Crystal structure of mannanase 26A from Pseudomonas cellulosa and analysis of residues involved in substrate binding.
Related PDB 1j9y
Related UniProtKB P49424
[3]
Resource
Comments
Medline ID
PubMed ID 12203498
Journal Angew Chem Int Ed Engl
Year 2002
Volume 41
Pages 2824-7
Authors Ducros VM, Zechel DL, Murshudov GN, Gilbert HJ, Szabo L, Stoll D, Withers SG, Davies GJ
Title Substrate distortion by a beta-mannanase: snapshots of the Michaelis and covalent-intermediate complexes suggest a B(2,5) conformation for the transition state.
Related PDB 1gvy 1gw1
Related UniProtKB P49424
[4]
Resource
Comments
Medline ID
PubMed ID 12841226
Journal Chem Commun (Camb)
Year 2003
Volume (12)
Pages 1327-9
Authors Jahn M, Stoll D, Warren RA, Szabo L, Singh P, Gilbert HJ, Ducros VM, Davies GJ, Withers SG
Title Expansion of the glycosynthase repertoire to produce defined manno-oligosaccharides.
Related PDB 1odz
Related UniProtKB P49424
[5]
Resource
Comments
Medline ID
PubMed ID 18799462
Journal J Biol Chem
Year 2008
Volume 283
Pages 34403-13
Authors Cartmell A, Topakas E, Ducros VM, Suits MD, Davies GJ, Gilbert HJ
Title The Cellvibrio japonicus mannanase CjMan26C displays a unique exo-mode of action that is conferred by subtle changes to the distal region of the active site.
Related PDB 2vx4 2vx5 2vx6 2vx7
Related UniProtKB B3PGI1
[6]
Resource
Comments X-RAY CRYSTALLOGRAPHY (1.45 ANGSTROMS) OF 27-362 IN COMPLEX WITH ZINC.
Medline ID
PubMed ID 18455734
Journal J Mol Biol
Year 2008
Volume 379
Pages 535-44
Authors Yan XX, An XM, Gui LL, Liang DC
Title From structure to function: insights into the catalytic substrate specificity and thermostability displayed by Bacillus subtilis mannanase BCman.
Related PDB 2qha
Related UniProtKB Q5PSP8
[7]
Resource
Comments
Medline ID
PubMed ID 19441796
Journal Biochemistry
Year 2009
Volume 48
Pages 7009-18
Authors Tailford LE, Ducros VM, Flint JE, Roberts SM, Morland C, Zechel DL, Smith N, Bjornvad ME, Borchert TV, Wilson KS, Davies GJ, Gilbert HJ
Title Understanding how diverse beta-mannanases recognize heterogeneous substrates.
Related PDB 2whk 2whm
Related UniProtKB O05512 P49424
[8]
Resource
Comments
Medline ID
PubMed ID
Journal Process Biochem
Year 2010
Volume 45
Pages 1203-13
Authors van Zyl WH, Rose SH, Trollope K, Gorgens JF
Title Fungal beta-mannanases: Mannan hydrolysis, heterologous production and biotechnological applications.
Related PDB
Related UniProtKB

Comments
This enzyme belongs to the glycosidase family-26, which adopts (alpha/beta)8 barrel structure.
According to the literature [7], this enzyme in family-26 hydrolyzes only mannan and galactomannan, whereas the counterpart enzymes from family-5 hydrolyze glucomannan as well as mannnan and galactomannan.
Moreover, according to the literature [5], this enzyme is an exo-acting mannanase, producing disaccharide, mannobiose, or galactomannobiose, from the non-reducing end of mannan or galactomannan, whereas most of homologous enzymes (S00911 and M00346 in EzCatDB) are endo-mannanases.
According to the literature [2], [3] and [5], this enzyme catalyzes the following reaction:
(0) Arg217, Tyr297 and His220 modulate the nucleophilic residue, Glu338, whereas the sidechain of Trp226 modulates Acid-base, Glu221. The mannopyranoside at -1 subsite adopts a 1S5 Skew boat conformation.
(1) Glu221 acts as a general acid to protonate the leaving oxygen in mannan, whereas Glu338 approaches the C1 atom of substrate mannan as a nucleophile. This process leads to an oxocarbenium-like transition-state (Boat conformation; B2,5). The -1 subsite in the transition-state is stabilized by His220 and Trp373.
(2) Glu338 makes a nucleophilic attack on the C1 atom of mannosyl group, to form a covalent intermediate, whereas the leaving group is cleaved from mannosyl group at subsite -1.
(3) Glu221 acts as a general base to deprotonate a water molecule, to activate it.
(4) The activated water makes a nucleophilic attack on the C1 atom of the covalent intermediate. Finally, the reaction completes.

Created Updated
2012-02-08 2012-05-14