DB code: S00911

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 S00912 S00915 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	CAZy	Pfam	RefSeq
Q5PSP8		Beta-1,4-mannanase EC 3.2.1.78	GH26 (Glycoside Hydrolase Family 26)	PF02156 (Glyco_hydro_26) [Graphical View]
O05512	Mannan endo-1,4-beta-mannosidase	EC 3.2.1.78 Beta-mannanase 1,4-beta-D-mannan mannanohydrolase	GH26 (Glycoside Hydrolase Family 26)	PF02156 (Glyco_hydro_26) [Graphical View]	NP_388469.2 (Protein) NC_000964.3 (DNA/RNA sequence)
P49424	Mannan endo-1,4-beta-mannosidase	EC 3.2.1.78 Mannanase A	GH26 (Glycoside Hydrolase Family 26)	PF02156 (Glyco_hydro_26) [Graphical View]	YP_001983229.1 (Protein) NC_010995.1 (DNA/RNA sequence)

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	Subcellular location
Q5PSP8	Q5PSP8_BACSU
O05512	MANB1_BACSU	Random hydrolysis of (1->4)-beta-D-mannosidic linkages in mannans, galactomannans and glucomannans.	Secreted (Potential).
P49424	MANA_CELJU	Random hydrolysis of (1->4)-beta-D-mannosidic linkages in mannans, galactomannans and glucomannans.

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

Compound table
	Substrates			Products		Intermediates
KEGG-id	C02492	C00883	C00001	C02492	C00883	I00118
E.C.
Compound	1,4-beta-D-Mannan	Galactomannan	H2O	1,4-beta-D-Mannan	Galactomannan	Peptidyl-Glu-D-mannan
Type	polysaccharide	polysaccharide	H2O	polysaccharide	polysaccharide
ChEBI		27680 27680	15377 15377		27680 27680
PubChem		439336 439336	22247451 962 22247451 962		439336 439336

2qhaA00	Unbound	Unbound		Unbound	Unbound	Unbound
2qhaB00	Unbound	Unbound		Unbound	Unbound	Unbound
2whkA00	Unbound	Unbound		Unbound	Unbound	Unbound
3cbwA00	Unbound	Unbound		Unbound	Unbound	Unbound
3cbwB00	Unbound	Unbound		Unbound	Unbound	Unbound
1gvyA00	Analogue:BMA-BMA-MBF-NIN	Unbound		Unbound	Unbound	Unbound
1gw1A00	Analogue:BMA-BMA-MBF-NIN	Unbound		Unbound	Unbound	Intermediate-analogue:BMA-BMA-MAF
1j9yA00	Unbound	Unbound		Unbound	Unbound	Unbound
1odzA00	Unbound	Unbound		Analogue:MAN-BMA	Unbound	Unbound
1odzB00	Unbound	Unbound		Analogue:MAN-BMA	Unbound	Unbound
1r7oA00	Unbound	Unbound		Unbound	Unbound	Unbound
2whmA00	Unbound	Unbound		Analogue:MAN-BMA	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

2qhaA00	ARG 163;HIS 166;GLU 167;TRP 172;TYR 242;GLU 266;TRP 298
2qhaB00	ARG 163;HIS 166;GLU 167;TRP 172;TYR 242;GLU 266;TRP 298
2whkA00	ARG 163;HIS 166;GLU 167;TRP 172;TYR 242;GLU 266;TRP 298
3cbwA00	ARG 189;HIS 192;GLU 193;TRP 198;TYR 268;GLU 292;TRP 324
3cbwB00	ARG 189;HIS 192;GLU 193;TRP 198;TYR 268;GLU 292;TRP 324
1gvyA00	ARG 208;HIS 211;;TRP 217;TYR 285;GLU 320;TRP 360				mutant E212A
1gw1A00	ARG 208;HIS 211;;TRP 217;TYR 285;GLU 320;TRP 360				mutant E212A
1j9yA00	ARG 208;HIS 211;GLU 212;TRP 217;TYR 285;GLU 320;TRP 360
1odzA00	ARG 208;HIS 211;GLU 212;TRP 217;TYR 285;;TRP 360				mutant E320G
1odzB00	ARG 208;HIS 211;GLU 212;TRP 217;TYR 285;;TRP 360				mutant E320G
1r7oA00	ARG 208;HIS 211;GLU 212;TRP 217;TYR 285;GLU 320;TRP 360
2whmA00	ARG 208;HIS 211;GLU 212;TRP 217;TYR 285;;TRP 360				mutant E320G

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], a homologous enzyme (S00915 in EzCatDB) is an exo-acting mannanase, producing disaccharide, mannobiose, or galactomannobiose, from the non-reducing end of mannan or galactomannan, whereas this enzyme and other homologous enzyme (M00346 in EzCatDB) are endo-mannanases. According to the literature [2], [3] and [5], this enzyme catalyzes the following reaction: (0) Arg163, Tyr242 and His166 (of 2qha) modulate the nucleophilic residue, Glu266, whereas the sidechain of Trp172 modulates Acid-base, Glu167. The mannopyranoside at -1 subsite adopts a 1S5 Skew boat conformation. (1) Glu167 acts as a general acid to protonate the leaving oxygen in mannan, whereas Glu266 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 His166 and Trp298. (2) Glu266 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) Glu167 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.

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], a homologous enzyme (S00915 in EzCatDB) is an exo-acting mannanase, producing disaccharide, mannobiose, or galactomannobiose, from the non-reducing end of mannan or galactomannan, whereas this enzyme and other homologous enzyme (M00346 in EzCatDB) are endo-mannanases.
According to the literature [2], [3] and [5], this enzyme catalyzes the following reaction:
(0) Arg163, Tyr242 and His166 (of 2qha) modulate the nucleophilic residue, Glu266, whereas the sidechain of Trp172 modulates Acid-base, Glu167. The mannopyranoside at -1 subsite adopts a 1S5 Skew boat conformation.
(1) Glu167 acts as a general acid to protonate the leaving oxygen in mannan, whereas Glu266 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 His166 and Trp298.
(2) Glu266 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) Glu167 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