RESUMO
The histone-like proteins (HU) belong to a family of DNA architectural proteins that stabilize nucleoprotein complexes. We found a putative HU protein (TgGlmHMM_3045) in Toxoplasma gondii genome that was homologous to the bacterial HU protein. This putative sequence was located in the scaffold TGG_995361 of the chromosome 10. The sequence included the prokaryotic bacterial histone-like domain, KFGSLGlRRRGERVARNPRT (ID number PS00045). HU protein sequences were also found in Plasmodium falciparum, Neospora caninum, Theileria parva and Theileria annulata. We found that the homology of the putative HU protein in Apicomplexa was greater with bacterial histone-like proteins than with eukaryotic histone proteins. The phylogenetic tree indicated that the putative HU protein genes were acquired in Apicomplexa by means of a secondary endosymbiotic event from red algae and later they were transferred from the apicoplast organelle to the nuclear genome.
Assuntos
Genoma de Protozoário , Histonas/genética , Proteínas de Protozoários/genética , Toxoplasma/genética , Sequência de Aminoácidos , Animais , Biologia Computacional , DNA de Protozoário/genética , Histonas/metabolismo , Dados de Sequência Molecular , Proteínas de Protozoários/metabolismo , Homologia de Sequência de AminoácidosRESUMO
The serine-rich (SR) protein family is involved in the pre-mRNA splicing process and the DNA sequences of the corresponding genes are highly conserved in the metazoan organisms. The mammalian SR proteins consist of one or two characteristic RNA binding domains (RBD), containing the signature sequences RDAEDA and SWQDLKD and a RS (arginine/serine-rich) domain. We used the amino acid and nucleotide sequences deposited in GenBank and Swiss-Prot databases to perform a phylogenetic analysis using bioinformatics tools. The results of the phylogenetic trees suggest that this family has evolved by several gene duplication events as a result of a positive selection mechanism.