2R49

Mutational and Structural Studies of E85I Reveal the Flexible Loops of Fibrobacter succinogenes 1,3-1,4-beta-D-GlucanaseGlucanase

Summary for 2R49

• Entry DOI: 10.2210/pdb2r49/pdb
• Related: 1MVE 1ZM1 2R4A
• Descriptor: Beta-glucanase, CALCIUM ION, CESIUM ION, ... (4 entities in total)
• Functional Keywords: 1, 3-1, 4-beta-d-glucanase, jellyroll beta-sandwich ca ion, glycosidase, hydrolase
• Biological source: Fibrobacter succinogenes
• Total number of polymer chains: 1
• Total formula weight: 27057.58

Authors

Tsai, L.C. (deposition date: 2007-08-30, release date: 2008-09-02, Last modification date: 2025-08-06)

Primary citation

Tsai, L.C.,Huang, H.C.,Hsiao, C.H.,Chiang, Y.N.,Shyur, L.F.,Lin, Y.S.,Lee, S.H.
Mutational and structural studies of the active-site residues in truncated Fibrobacter succinogenes1,3-1,4-beta-D-glucanase.
Acta Crystallogr.,Sect.D, 64:1259-1266, 2008

PubMed Abstract: 1,3-1,4-beta-D-Glucanases (EC 3.2.1.73) specifically hydrolyze beta-1,4-glycosidic bonds located prior to beta-1,3-glycosidic linkages in lichenan or beta-D-glucans. It has been suggested that truncated Fibrobacter succinogenes 1,3-1,4-beta-D-glucanase (TFsbeta-glucanase) can accommodate five glucose rings in its active site upon enzyme-substrate interaction. In this study, 12 mutant enzymes were created by mutating the conserved residues Gln70, Asn72, Gln81 and Glu85 proposed to bind to substrate subsites +1 and +2 and the catalytic properties of these mutants were determined. The most significant change in catalytic activity was observed on mutation of Gln70, with a 299-fold and 498-fold lower k(cat)/K(m) for the mutants Q70A and Q70I, respectively, compared with the wild-type enzyme. Mutagenesis, kinetic and structural studies revealed that the conserved residues surrounding the active site of TFsbeta-glucanase at substrate subsites +1 and +2 play an important role in its catalytic function, with the following order of importance: Gln70 > Asn72 > Glu85 > Gln81. The crystal structure of mutant E85I was determined at 2.2 A resolution. Further analysis of the E85I mutant structure revealed that the loop located at the concave site moved approximately 2 A from its position in the native enzyme complex without changing the core structure.

PubMed: 19018102
DOI: 10.1107/S0907444908033428

Experimental method

X-RAY DIFFRACTION (2.2 Å)