Structure of an ABC transporter solute-binding protein specific for the amino sugars glucosamine and galactosamine.
The uptake of exogenous solutes by prokaryotes is mediated by transport systems embedded in the plasma membrane. In many cases, a solute-binding protein (SBP) is utilized to bind ligands with high affinity and deliver them to the membrane-bound components responsible for translocation into the cytoplasm. In the present study, Avi_5305, an Agrobacterium vitis SBP belonging to Pfam13407, was screened by differential scanning fluorimetry (DSF) and found to be stabilized by D-glucosamine and D-galactosamine. Avi_5305 is the first protein from Pfam13407 shown to be specific for amino sugars, and co-crystallization resulted in structures of Avi_5305 bound to D-glucosamine and D-galactosamine. Typical of Pfam13407, Avi_5305 consists of two α/β domains linked through a hinge region, with the ligand-binding site located in a cleft between the two domains. Comparisons with Escherichia coli ribose-binding protein suggest that a cation-π interaction with Tyr168 provides the specificity for D-glucosamine/D-galactosamine over D-glucose/D-galactose.
Department of Physics, DDU Gorakhpur University, Gorakhpur 273 009, India.
Umesh
U
Yadava
Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Matthew W
MW
Vetting
Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Nawar
N
Al Obaidi
Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
Michael S
MS
Carter
Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, USA.
John A
JA
Gerlt
Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Steven C
SC
Almo
D018528:ATP-Binding Cassette Transporters / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D005688:Galactosamine / Q000378:metabolism*; D005944:Glucosamine / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D005688:Galactosamine; D005944:Glucosamine
Agrobacterium vitis; Avi_5305; Pfam13407; Thermofluor; differential scanning fluorimetry; solute-binding protein