Entamoeba histolytica: comparative genomics of the pre-mRNA 3' end processing machinery.

We report here the pre-mRNA 3' end processing machinery in Entamoeba histolytica. Comparative analysis of the putative sequences participating in the pre-mRNA 3' end processing of E. histolytica genes shows similitude and differences to those described for yeast and human transcripts. By a genomic survey, we identified 16 putative genes encoding for cleavage/polyadenylation factors in this parasite. E. histolytica pre-mRNA 3' end processing machinery does not seem to contain homologous genes coding for human Symplekin, CFIm59, and CFIm68 proteins, neither sequences related to yeast Pta1p and Hrp1p. Protein sequence comparisons among E. histolytica, yeast, and human showed little variation in their functional domains through evolutive scale. E. histolytica pre-mRNA 3' end processing machinery appears to be in an intermediate evolutionary position between mammals and yeast. From these analyses, we propose a hypothetical working model for the pre-mRNA 3' end processing machinery in E. histolytica.