X-ray structure of glucose/galactose receptor from Salmonella typhimurium in complex with the physiological ligand, (2R)-glyceryl-β-d- galactopyranoside
2009 (English)In: The FEBS Journal, ISSN 1742-464X, E-ISSN 1742-4658, Vol. 276, no 7, 2116-2124 p.Article in journal (Refereed) Published
Periplasmic binding proteins are abundant in bacteria by virtue of their essential roles as high-affinity receptors in ABC transport systems and chemotaxis. One of the best studied of these receptors is the so-called glucose/galactose-binding protein (GBP). In the present paper, we report the x-ray structure of the Salmonella typhimurium protein bound to the physiologically relevant ligand, (2R)-glyceryl-b-D-galactopyranoside (GGal), solved by molecular replacement, and refined to 1.87 Å resolution with R and R-free values of 17% and 22%. The structure identifies three amino acid residues that are diagnostic of GGal binding (Thr110, Asp154 and Gln261), as opposed to binding to the monosaccharides, glucose and galactose. These three residues are conserved in essentially all available GBP sequences, indicating that the binding of GGal is the rule rather than the exception for receptors of this type. The role of GGal in bacterial biology is discussed. Further, comparison of the available structures provides the most complete description of the conformational changes of GBP to date. The structures follow a smooth and continuous path from the most closed structure (that bound to GGal) to the most open one (an apo structure).
Place, publisher, year, edition, pages
2009. Vol. 276, no 7, 2116-2124 p.
Galactose uptake, Glucose/galactose-binding protein, Glyceryl galactoside, Lactose uptake, Salmonella enterica serovar Typhimurium
IdentifiersURN: urn:nbn:se:uu:diva-142142DOI: 10.1111/j.1742-4658.2009.06945.xISI: 000264021900028PubMedID: 19292879OAI: oai:DiVA.org:uu-142142DiVA: diva2:387045
FunderSwedish Research Council