2O7I

The X-ray crystal structure of a thermophilic cellobiose binding protein bound with cellobiose

Summary for 2O7I

• Entry DOI: 10.2210/pdb2o7i/pdb
• Related: 2O7J
• Related PRD ID: PRD_900005
• Descriptor: Oligopeptide ABC transporter, periplasmic oligopeptide-binding protein, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose (3 entities in total)
• Functional Keywords: periplasmic binding protein, cellulose, thermophilic proteins, cellobiose binding protein, sugar binding protein
• Biological source: Thermotoga maritima
• Total number of polymer chains: 1
• Total formula weight: 69070.92

Authors

Cuneo, M.J.,Hellinga, H.W. (deposition date: 2006-12-11, release date: 2007-03-20, Last modification date: 2023-08-30)

Primary citation

Cuneo, M.J.,Beese, L.S.,Hellinga, H.W.
Structural Analysis of Semi-specific Oligosaccharide Recognition by a Cellulose-binding Protein of Thermotoga maritima Reveals Adaptations for Functional Diversification of the Oligopeptide Periplasmic Binding Protein Fold.
J.Biol.Chem., 284:33217-33223, 2009

PubMed Abstract: Periplasmic binding proteins (PBPs) constitute a protein superfamily that binds a wide variety of ligands. In prokaryotes, PBPs function as receptors for ATP-binding cassette or tripartite ATP-independent transporters and chemotaxis systems. In many instances, PBPs bind their cognate ligands with exquisite specificity, distinguishing, for example, between sugar epimers or structurally similar anions. By contrast, oligopeptide-binding proteins bind their ligands through interactions with the peptide backbone but do not distinguish between different side chains. The extremophile Thermotoga maritima possesses a remarkable array of carbohydrate-processing metabolic systems, including the hydrolysis of cellulosic polymers. Here, we present the crystal structure of a T. maritima cellobiose-binding protein (tm0031) that is homologous to oligopeptide-binding proteins. T. maritima cellobiose-binding protein binds a variety of lengths of beta(1-->4)-linked glucose oligomers, ranging from two rings (cellobiose) to five (cellopentaose). The structure reveals that binding is semi-specific. The disaccharide at the nonreducing end binds specifically; the other rings are located in a large solvent-filled groove, where the reducing end makes several contacts with the protein, thereby imposing an upper limit of the oligosaccharides that are recognized. Semi-specific recognition, in which a molecular class rather than individual species is selected, provides an efficient solution for the uptake of complex mixtures.

PubMed: 19801540
DOI: 10.1074/jbc.M109.041624

Experimental method

X-RAY DIFFRACTION (1.5 Å)