Structural modeling of troponin I, slow skeletal muscle in Homo sapiens (Human)

Abstract

Troponin I (TnI) is the inhibitory subunit of the troponin complex in the sarcomere thin filament of the striated muscle and plays a critical role in the calcium regulation of contraction and relaxation. However, its 3D structure remains unknown until now. Thus, modeling and understanding of this protein are significant. Modeling the predicted 3D structure helps to analyze the function of this protein. The amino acid sequence of Troponin I, slow skeletal muscle was retrieved from the Uniprot database (UniProt ID: P19237). Prediction of protein secondary structure was obtained using the CFSSP website (Chou & Fasman Secondary Structure Prediction Server), while for homology modeling, Phyre2 software was used. While PyMol and Chimera visualization software was used for The structural comparison between the protein predicted model and the templates. Troponin I, the Three-dimensional (3D) structure of slow skeletal muscle is innovative to the extent that it has no protein modeling structure among all organisms that contained such protein up to the present time. Troponin I, slow skeletal muscle was obtained from the UniProt database (P19237). BLASTp in the NCBI database was carried out to identify resemble sequence, The secondary structure prediction analysis showed 165 residues, 88.2% involved in the formation of the helix, 76 residues involved in the formation of beta-sheet and 25 residues, 13.4% involved in the formation of turn CFSSP server (Chou & Fasman Secondary Structure Prediction Server). Three different model evaluation web servers (PROCHECK, Verify 3D, and ERRAT). 89% of residues had located in favored regions, 8.1 % of residues had situated in additional allowed regions, and 1.2% residues in generously allowed regions 1.7% disallowed regions. This indicating the model generated has good stereochemical quality with accurate structure geometry. Troponin I, slow skeletal muscle is so novel to an extent that it has no three-dimensional (3D) structure among all organisms that contained such protein up to the present time. So, in this study, the predicted 3D model was compared with a template, due to the absence of any known 3D structure, and provide useful information to this protein since this protein is essential in the medical sector.