In silico characterization of the E3 ubiquitin CRL1 ligase complex (Cullin RING-ligases) in Leishmania infantum

Abstract

The ubiquitin proteasome system (SUP) is primarily responsible for intracellular proteolysis in eukaryotes. Ubiquitination occurs through the action of enzymes E1 (ubiquitin-activating enzyme), E2 (ubiquitin-carrying enzyme) and E3 (ubiquitin-ligases), essential in the recognition and transfer of ubiquitin to the target protein. These can be directed to the proteasome for degradation or have their functions regulated. Protozoan parasites that alternate hosts in their life cycles have intracellular proteolysis as an essential process for successful parasitism. Little is known about SUP in many parasites, including trypanosomatids of the genus Leishmania, responsible for causing leishmaniasis. In Brazil, the species Leishmania infantum is the etiological agent of visceral leishmaniasis (VL), the most severe form of the disease, which can be fatal if not treated. The Leishmania proteasome has subunits with high degree of identity with the humans proteasome and has been the target of drugs for the treatment of leishmaniasis. Recently, the enzymes E1, E2 and deubiquitinases from Leishmania mexicana were characterized demonstrating their essential role in the proliferation and infectivity of this species. However Leishmania E3 ubiquitin ligases remain understudied. This project proposes in silico analyzes for the structural and phylogenetic characterization of the genes, LINF_110018100, LINF_210005300, LINF_24002910 and LINF_240015400, orthologs to the human genes SKP1, RBX1, CUL1 and F-box like Protein-FBP respectively. These are components of the largest and best studied class of E3 ubiquitin ligases in humans, the Cullin RING ligases (CRLs) or SCF1. Previous results from the current AR-FAPESP (2020/15771-6) by our group demonstrated that the CRL complex exists in L. infantum and the interactions between its components were validated by assays in mammalian cellular models. However, structural modeling studies and phylogenetic analyzes of these genes have not been developed. This project aims to fill this gap in AR-FAPESP and will contribute to the characterization of these parasite genes at a structural and phylogenetic level.