2GH9

Thermus thermophilus maltotriose binding protein bound with maltotriose

Summary for 2GH9

• Entry DOI: 10.2210/pdb2gh9/pdb
• Related: 2GHA 2GHB
• Related PRD ID: PRD_900009
• Descriptor: maltose/maltodextrin-binding protein, alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose (3 entities in total)
• Functional Keywords: mbp, thermus thermophilus, maltose binding protein, thermophilic protein, periplasmic binding protein, sugar binding protein
• Biological source: Thermus thermophilus
• Total number of polymer chains: 1
• Total formula weight: 42608.90

Authors

Cuneo, M.J.,Changela, A.,Beese, L.S.,Hellinga, H.W. (deposition date: 2006-03-27, release date: 2007-02-06, Last modification date: 2024-02-14)

Primary citation

Cuneo, M.J.,Changela, A.,Beese, L.S.,Hellinga, H.W.
Structural adaptations that modulate monosaccharide, disaccharide, and trisaccharide specificities in periplasmic maltose-binding proteins.
J.Mol.Biol., 389:157-166, 2009

PubMed Abstract: Periplasmic binding proteins comprise a superfamily that is present in archaea, prokaryotes, and eukaryotes. Periplasmic binding protein ligand-binding sites have diversified to bind a wide variety of ligands. Characterization of the structural mechanisms by which functional adaptation occurs is key to understanding the evolution of this important protein superfamily. Here we present the structure and ligand-binding properties of a maltotriose-binding protein identified from the Thermus thermophilus genome sequence. We found that this receptor has a high affinity for the trisaccharide maltotriose (K(d)<1 microM) but little affinity for disaccharides that are transported by a paralogous maltose transport operon present in T. thermophilus. Comparison of this structure to other proteins that adopt the maltose-binding protein fold but bind monosaccharides, disaccharides, or trisaccharides reveals the presence of four subsites that bind individual glucose ring units. Two loops and three helical segments encode adaptations that control the presence of each subsite by steric blocking or hydrogen bonding. We provide a model in which the energetics of long-range conformational equilibria controls subsite occupancy and ligand binding.

PubMed: 19361522
DOI: 10.1016/j.jmb.2009.04.008

Experimental method

X-RAY DIFFRACTION (1.95 Å)