title: A computational model of the LGI1 protein suggests a common binding site for ADAM proteins.
abstract: Mutations of human leucine-rich glioma inactivated (LGI1) gene encoding the epitempin protein cause autosomal dominant temporal lateral epilepsy (ADTLE), a rare familial partial epileptic syndrome. The LGI1 gene seems to have a role on the transmission of neuronal messages but the exact molecular mechanism remains unclear. In contrast to other genes involved in epileptic disorders, epitempin shows no homology with known ion channel genes but contains two domains, composed of repeated structural units, known to mediate protein-protein interactions.A three dimensional in silico model of the two epitempin domains was built to predict the structure-function relationship and propose a functional model integrating previous experimental findings. Conserved and electrostatic charged regions of the model surface suggest a possible arrangement between the two domains and identifies a possible ADAM protein binding site in the β-propeller domain and another protein binding site in the leucine-rich repeat domain. The functional model indicates that epitempin could mediate the interaction between proteins localized to different synaptic sides in a static way, by forming a dimer, or in a dynamic way, by binding proteins at different times.The model was also used to predict effects of known disease-causing missense mutations. Most of the variants are predicted to alter protein folding while several other map to functional surface regions. In agreement with experimental evidence, this suggests that non-secreted LGI1 mutants could be retained within the cell by quality control mechanisms or by altering interactions required for the secretion process.
authors.affiliation: Department of Biology, University of Padova, Padova, Italy.
authors.forename: Emanuela
authors.initials: E
authors.lastname: Leonardi
authors.forename: Simonetta
authors.initials: S
authors.lastname: Andreazza
authors.forename: Stefano
authors.initials: S
authors.lastname: Vanin
authors.forename: Giorgia
authors.initials: G
authors.lastname: Busolin
authors.forename: Carlo
authors.initials: C
authors.lastname: Nobile
authors.forename: Silvio C E
authors.initials: SC
authors.lastname: Tosatto
mesh_terms: D051722:ADAM Proteins / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D019295:Computational Biology / Q000379:methods*; D019143:Evolution, Molecular; D006031:Glycosylation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D000090263:Leucine-Rich Repeat Proteins; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020125:Mutation, Missense / Q000235:genetics; D010802:Phylogeny; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D040681:Structural Homology, Protein
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C116499:LGI1 protein, human; D000090263:Leucine-Rich Repeat Proteins; D008024:Ligands; D011506:Proteins; D051722:ADAM Proteins