title: Structural insights into genetic variants of Na(+)/glucose cotransporter SGLT1 causing glucose-galactose malabsorption: vSGLT as a model structure.
abstract: Current advances in structural biology provide valuable insights into structure-function relationship of membrane transporters by solving crystal structures of bacterial homologs of human transporters. Therefore, scientists consider bacterial transporters as useful structural models for designing of drugs targeted in human diseases. The functional homology between Vibrio parahaemolyticus Na(+)/galactose transporter (vSGLT) and Na(+)/glucose cotransporter SGLT1 has been well established a decade ago. Now the crystal structure of vSGLT is considered quite valuable in explaining not only the cotransport mechanisms, but it also acts as a representative protein in understanding the protein stability and amino acid interactions within the core structure. We investigated the molecular mechanisms of genetic variations in SGLT1 that cause glucose-galactose malabsorption (GGM) defects using the crystal structure of vSGLT as a model sugar transporter. Our in silico mutagenesis and modeling analysis suggest that the GGM genetic variations lead to conformational changes either by structure destabilization or by formation of unnecessary interaction within the core structure of SGLT1 thereby explaining the genetic defects in Na(+) dependent sugar translocation across the cell membrane.
authors.affiliation: Max Planck Institute of Molecular Physiology, Otto-Hahn-Strasse 11, 44227 Dortmund, Germany. mraja@ualberta.ca
authors.forename: Mobeen
authors.initials: M
authors.lastname: Raja
authors.forename: Rolf K H
authors.initials: RK
authors.lastname: Kinne
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics*; D005690:Galactose / Q000378:metabolism*; D014644:Genetic Variation; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D006860:Hydrogen Bonding; D007408:Intestinal Absorption / Q000235:genetics; D008286:Malabsorption Syndromes / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D051269:Sodium-Glucose Transporter 1 / Q000737:chemistry* / Q000235:genetics*; D040681:Structural Homology, Protein
chemical_list: D001426:Bacterial Proteins; C495674:SLC5A1 protein, human; D051269:Sodium-Glucose Transporter 1; D005947:Glucose; D005690:Galactose