User:Mariel Feliciano

From Proteopedia

Glucose/Galactose-binding protein

Figure 1 Superposition of open (orange, PDB ID 2fw0) and closed (cyan, PDB ID 2fvy) conformations of GGBP

Figure 2 Structures color-coded from least(cyan) to most(maroon) conserved residues as defined by Consurf

Glucose/Galactose-binding protein (GGBP) from E. coli is found in the periplasm of the bacterium. This protein is involved in the transport of glucoseas well as the chemotaxis toward it. It is composed of two Rossman folds separated by three short segments of amino acids termed the because of their role in the opening/closing mechanism of the protein. The protein exists in two conformations: glucose-bound (closed) and unbound (open) (Figure 1). Upon ligand binding, changes in the torsional angles of the amino acids that compose the hinges produce a conformational change between the two domains that stabilize the closed conformation. Analysis of the structure with Consurf ^[1](Figure 2) shows that amino acids that line the and amino acids that compose the hinges are the most conserved. Despite its homology with other sugar-binding proteins like ribose-binding protein (RBP), the changes in torsional angles of the amino acids that compose the hinges and trigger the conformational changes between domains differ in both proteins. One of the structures reported by Borrok, M.J., Kiessling, L.L., and Forest, K.T. ^[2] (PDB ID 2FW0) is the first crystal structure of the protein in its open conformation. The other structure reported by these authors ^[2] (PDB ID 2FVY) is an ultra-high resolution (0.95Å) crystal structure of the glucose-bound protein.

Scenes

References

1. ↑ Landau, M., Mayrose, I., Rosenberg, Y., Glaser, F., Martz, E., Pupko, T., et al. (2005). ConSurf 2005: The projection of evolutionary conservation scores of residues on protein structures. Nucleic Acids Research, 33(Web Server issue), W299-302.
2. ↑ ^{2.0 2.1} Borrok, M. J., Kiessling, L. L., & Forest, K. T. (2007). Conformational changes of glucose/galactose-binding protein illuminated by open, unliganded, and ultra-high-resolution ligand-bound structures. Protein Science : A Publication of the Protein Society, 16(6), 1032-1041.