Assessing the Functional Properties of the TMCO1 Sequence Variants by Using In Silico Analyses

Transmembrane and Coiled-Coil Domains 1 (TMCO1) protein is encoded by TMCO1 gene consists of 7 exons. Previous studies have identified multiple TMCO1 variants in patients with cerebro-facio-thoracic dysplasia (CFTD) and TMCO1 locus was also shown to be associated with primary open angle glaucoma (POAG). However, there are limited number of research exist reporting associations of the TMCO1 gene sequence variants and majority of the findings affirm the pathogenicity of the nonsense and frameshift TMCO1 variants and their associations with clinical phenotypes. Thus functional properties of the single nucleotide variants causing amino acid changes in the TMCO1 are yet to be comprehensively elucidated. In this study, we evaluated the effects of amino acid substitutions on protein structure, identified their putative roles in post-translational modifications (PTM) and in regulatory mechanism for TMCO1 protein. We classified 41 missense variants as pathogenic based on combined scores of common in silico tools (SIFT, MutationTaster2, Polyphen2). Of these 41 variants, four (p.K211Q, p.K105E, p.S235F, p.K237R) were identified to be located in PTMs and regulatory protein binding sites; thus they were proposed to be putative functional variants. Moreover, rs1387528611 (p.Lys128Gln) had also strong evidence (RegulomeDB score=2b) for its possible regulatory function. The results of our in silico analyses highlight the functional importance of the missense TMCO1 variants that may contribute to the TMCO1-associated disease phenotypes and further in vivo evaluation yet to be needed to uncover their role in human diseases