Análise in silico do sistema ubiquitina-proteassoma em Biomphalaria glabrata

Abstract

Schistosomiasis is a parasitic disease caused by helminths of the genus Schistosoma that affects more than 200 million people worldwide. Brazil is the South American country with the highest incidence of the disease, due, among other factors, to the vast territorial distribution of mollusks of the genus Biomphalaria. B. glabrata, highly susceptible and main responsible for S. mansoni transmission. Much of the biology of the mollusk is known, but studies involving its gene regulation are still scarce. The ubiquitin-proteasome system (USP) is one of the major gene regulators since it is capable of performing post-translational regulation by labeling target substrates by ubiquitin, which are subsequently targeted for cellular signaling and/or degraded by the 26S proteasome. This system is related to several mechanisms, including immune responses. Thus, the objective of this work was to predict, characterize and evaluate the expression of genes involved in the ubiquitination pathway using bioinformatics tools in genome and transcriptome data from B. glabrata. The alleged USP genes and proteins in B. glabrata were predicted using BLASTp using proteins from model organisms as queries. We characterize these putative proteins using the PFAM and CDD software describing the conserved domains and the active sites. Phylogenetic analysis was performed using ClustalX2 and MEGA5.2. Expression evaluation was performed from 12 snail tissues using RPKM. A total of 86 sequences were identified: one ubiquitin sequence, 6 ubiquitin activating enzymes (E1), 22 ubiquitin conjugating enzymes (E2), 39 ubiquitin ligases (E3) enzymes and 18 accessory and adapter proteins. The main conserved domains of the proteins identified were Ubiquitin Family, UQ_con, HECT, U-box and domains homologous to RING finger. The active sites found were the lysine residues responsible for the polyubiquitin chains, cysteine residues that bind to ubiquitin, among others. Phylogeny showed a very well defined evolutionary distribution between all groups of sequences, corroborating with the tree of life. The ubiquitin sequence was the only with high expression profile found for all libraries, inferring its wide range of performance. These results evidenced the presence, conservation and expression of USP data of B. glabrata, providing a basis for new knowledge involving this pathway in the study mollusk, as well as offering new ways of understanding the regulation of genes that confer the susceptibility/resistance of the snail, allowing greater perspectives for the control of schistosomiasis.