title: SLC4A11 Three-Dimensional Homology Model Rationalizes Corneal Dystrophy-Causing Mutations.
abstract: We studied the structural effects of point mutations of a membrane protein that cause genetic disease. SLC4A11 is a membrane transport protein (OH-/H+/NH3/H2O) of basolateral corneal endothelium, whose mutations cause some cases of congenital hereditary endothelial dystrophy and Fuchs endothelial corneal dystrophy. We created a three-dimensional homology model of SLC4A11 membrane domain, using Band 3 (SLC4A1) crystal structure as template. The homology model was assessed in silico and by analysis of mutants designed on the basis of the model. Catalytic pathway mutants p.Glu675Gln, p.His724Arg, and p.His724Ala impaired SLC4A11 transport. p.Ala720Leu, in a region of extended structure of the proposed translocation pore, failed to mature to the cell surface. p.Gly509Lys, located in an open region at the core domain/gate domain interface, had wild-type level of transport function. The molecular phenotype of 37 corneal dystrophy-causing point mutants was rationalized, based on their location in the homology model. Four map to the substrate translocation pathway, 25 to regions of close transmembrane helix packing, three to the dimeric interface, and five lie in extramembraneous loops. The model provides a view of the spectrum of effects of disease mutations on membrane protein structure and provides a tool to analyze pathogenicity of additional newly discovered SLC4A11 mutants.
authors.affiliation: Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Katherine E
authors.initials: KE
authors.lastname: Badior
authors.affiliation: Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Kumari
authors.initials: K
authors.lastname: Alka
authors.affiliation: Department of Biochemistry, Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Casey
mesh_terms: D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D027321:Anion Transport Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D017920:Antiporters / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D002384:Catalysis; D017124:Conserved Sequence; D003317:Corneal Dystrophies, Hereditary / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D020022:Genetic Predisposition to Disease; D057809:HEK293 Cells; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D000072417:Protein Domains; D054730:Protein Interaction Domains and Motifs / Q000235:genetics; D055503:Protein Multimerization; D013329:Structure-Activity Relationship
chemical_list: D027321:Anion Transport Proteins; D017920:Antiporters; C425809:SLC4A11 protein, human
keywords: SLC4A11, homology modeling; congenital hereditary endothelial dystrophy (CHED), Fuchs endothelial dystrophy (FECD), corneal dystrophy