Literature summary for 3.2.1.39 extracted from

Wojtkowiak, A.; Witek, K.; Hennig, J.; Jaskolski, M.
Structures of an active-site mutant of a plant 1,3-beta-glucanase in complex with oligosaccharide products of hydrolysis (2013), Acta Crystallogr. Sect. D, 69, 52-62.

Cloned(Commentary)

Cloned (Comment)	Organism
gene gluB20-2, recombinant expression of C-terminally His-tagged mutant E259A in Escherichia coli strain BL21	Solanum tuberosum

Crystallization (Commentary)

Crystallization (Comment)	Organism
purified recombinant His-tagged mutant E259A in complex with laminarihexose, hanging drop vapour diffusion, mixing of 0.0015 ml of 7 mg/ml protein in 20 mM Tris-HCl, pH 8.0, with 0.0015 ml of reservoir solution containing 0.1 M sodium citrate, pH 5.6, 0.2 M ammonium acetate, 24% PEG 8000, 21°C, 2-7 days, crystals in form of bunched needles, single and larger crystals by use of streak-seeding, X-ray diffraction structure determination and analysis at 1.55-1.68 A, 3G and 7G crystal structures by molecular replacement	Solanum tuberosum

Crystallization (Comment)

Organism

purified recombinant His-tagged mutant E259A in complex with laminarihexose, hanging drop vapour diffusion, mixing of 0.0015 ml of 7 mg/ml protein in 20 mM Tris-HCl, pH 8.0, with 0.0015 ml of reservoir solution containing 0.1 M sodium citrate, pH 5.6, 0.2 M ammonium acetate, 24% PEG 8000, 21°C, 2-7 days, crystals in form of bunched needles, single and larger crystals by use of streak-seeding, X-ray diffraction structure determination and analysis at 1.55-1.68 A, 3G and 7G crystal structures by molecular replacement

Solanum tuberosum

Protein Variants

Protein Variants	Comment	Organism
E259A	site-directed mutagenesis, substitution of the nucleophilic residue, the active site mutant retains residual endoglucanase activity	Solanum tuberosum

Natural Substrates/ Products (Substrates)

Natural Substrates	Organism	Comment (Nat. Sub.)	Natural Products	Comment (Nat. Pro.)	Rev.	Reac.
additional information	Solanum tuberosum	plant endo-1,3-beta-glucanases hydrolyze (1,3)-beta-glucans, with very limited activity towards mixed (1,3,1,4)-beta-glucans and branched (1,3,1,6)-beta-glucans	?	-	?

Organism

Organism	UniProt	Comment	Textmining
Solanum tuberosum	Q70C53	gene gluB20-2	-

Purification (Commentary)

Purification (Comment)	Organism
recombinant His-tagged mutant E259A from Escherichia coli strain BL21 to homogeneity	Solanum tuberosum

Reaction

Reaction	Comment	Organism	Reaction ID
laminariheptaose + 3 H2O = laminaritriose + 2 laminaribiose	substrate binding structure and catalytic mechanism, overview	Solanum tuberosum	a

Substrates and Products (Substrate)

Substrates	Comment Substrates	Organism	Products	Comment (Products)	Rev.	Reac.
laminarihexose + H2O	active with the wild-type enzyme, but also the active site mutant E259A, that shows residual activity in the substrate complex crystal and cleaves the substrate in two different ways, generating trisaccharides and tetrasaccharides, mass spectrometry	Solanum tuberosum	laminaritriose + laminaritetraose	laminaritriose shows higher binding affinity and fully occupies the -1, -2 and -3 sites of the active-site cleft, even at a low molar excess of the substrate. At elevated substrate concentration laminaritetrose also occupies the active site, spanning the opposite sites +1, +2, +3 and +4 of the cleft	?
additional information	plant endo-1,3-beta-glucanases hydrolyze (1,3)-beta-glucans, with very limited activity towards mixed (1,3,1,4)-beta-glucans and branched (1,3,1,6)-beta-glucans	Solanum tuberosum	?	-	?

Synonyms

Synonyms	Comment	Organism
1,3-beta-glucanase	-	Solanum tuberosum
endo-1,3-beta-glucanase	-	Solanum tuberosum
GLUB20-2	-	Solanum tuberosum

General Information

General Information	Comment	Organism
evolution	the enzyme is a member of plant glycoside hydrolase family 17, GH17	Solanum tuberosum
additional information	the geometry of the active site cleft clearly precludes any (1,4)-beta-glucan topology at the subsites from -3 to +4 and could possibly accommodate beta-1,6-branching only at subsites +1 and +2. The glucose units at subsites -1 and -2 interact with highly conserved protein residues. In contrast, subsites -3, +3 and +4 are variable, suggesting that the mode of glucose binding at these sites may vary between different plant endo-1,3-beta-glucanases. Low substrate affinity is observed at subsites +1 and +2, as manifested by disorder of the glycosyl units there. Structure-function analysis, overview	Solanum tuberosum
physiological function	plant endo-1,3-beta-glucanases are involved in important physiological processes such as defence mechanisms, cell division and flowering. Endo-1,3-beta-glucanases in plants are believed to function as part of a defence mechanism against fungi by hydrolyzing the fungal cell wall, which is built mostly of (1,3)-beta-D-glucans	Solanum tuberosum