2V8M

Carbohydrate-binding of the starch binding domain of Rhizopus oryzae glucoamylase in complex with beta-cyclodextrin and maltoheptaose

Summary for 2V8M

• Entry DOI: 10.2210/pdb2v8m/pdb
• Related: 2V8L 2VQ4
• Descriptor: GLUCOAMYLASE A, alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose, SULFATE ION, ... (4 entities in total)
• Functional Keywords: hydrolase, carbohydrate binding
• Biological source: RHIZOPUS ORYZAE
• Total number of polymer chains: 4
• Total formula weight: 51838.71

Authors

Tung, J.-Y.,Liu, Y.-Y.,Sun, Y.-J. (deposition date: 2007-08-09, release date: 2008-08-19, Last modification date: 2024-05-08)

Primary citation

Tung, J.-Y.,Chang, M.D.-T.,Chou, W.-I.,Liu, Y.-Y.,Yeh, Y.,Chang, F.,Lin, S.,Qiu, Z.,Sun, Y.-J.
Crystal Structures of the Starch-Binding Domain from Rhizopus Oryzae Glucoamylase Reveal a Polysaccharide-Binding Path.
Biochem.J., 416:27-, 2008

PubMed Abstract: GA (glucoamylase) hydrolyses starch and polysaccharides to beta-D-glucose. RoGA (Rhizopus oryzae GA) consists of two functional domains, an N-terminal SBD (starch-binding domain) and a C-terminal catalytic domain, which are connected by an O-glycosylated linker. In the present study, the crystal structures of the SBD from RoGA (RoGACBM21) and the complexes with beta-cyclodextrin (SBD-betaCD) and maltoheptaose (SBD-G7) were determined. Two carbohydrate binding sites, I (Trp(47)) and II (Tyr(32)), were resolved and their binding was co-operative. Besides the hydrophobic interaction, two unique polyN loops comprising consecutive asparagine residues also participate in the sugar binding. A conformational change in Tyr(32) was observed between unliganded and liganded SBDs. To elucidate the mechanism of polysaccharide binding, a number of mutants were constructed and characterized by a quantitative binding isotherm and Scatchard analysis. A possible binding path for long-chain polysaccharides in RoGACBM21 was proposed.

PubMed: 18588504
DOI: 10.1042/BJ20080580

Experimental method

X-RAY DIFFRACTION (2.3 Å)