Structure‐Function Analysis of An Autophagy Factor from Crithidia Fasciculata , Cf ATG4.1, as The Potential Drug Target for The Emerging Parasitic And Infectious Disease

Abstract

Crithidia is an emerging parasite causing infectious disease and can switch host from insect to human. Crithidia parasites undergo autophagy to mobilize nutrients needed during starvation, to defend against starvation and for cellular remodeling. Autophagy is regulated using ATG proteins that work in sequence of pathways for the formation of autophagosomes. An essential ATG protein in autophagy is ATG4, a cysteine protease, due to its participation in the cleavage of ATG8. The hypothesis of this study is that to analyze autophagy pathway in C. fasciculata on ATG4.1 protein, and the computational analysis on the CfATG4.1 protein to determine the structure of the protein, the concomitant active binding site, and its functionality. Bioinformatics research and analysis were conducted on the CfATG4.1 using its amino acid sequence and its three-dimensional structure of the protein to analyze the active site as the target and use the ATG8 substrate for inhibitor binding studies. The preliminary results of this study on CfATG4 shows that the active site is conserved, has similar homologs and is evolutionary conserved across different species of Trypanosoma brucei, Trypanosoma cruzi, Leishmania major, Drosophila melanogaster, and Human ATG4s (HsATG). This suggests that CfATG4.1 belongs to the cysteine protease superfamily of proteins. The superimposable 3D- structure of the CfATG4.1 onto the HsATGB 3D-structure using PyMol resulted in the predicted structure for CfATG4.1. Therefore, the aim of this study is to focus on the conserved domains, the active catalytic site, and the 3D structure of CfATG4.1 to relate protein structure-function relationship and in the future, search for targeted screening of inhibitors.