ABSTRACT
In humans, mRNA polyadenylation involves the participation of about 20 factors in four main complexes that recognize specific RNA sequences. Notably, CFIm25, CPSF73, and PAP have essential roles for poly(A) site selection, mRNA cleavage, and adenosine residues polymerization. Besides the relevance of polyadenylation for gene expression, information is scarce in intestinal protozoan parasites that threaten human health. To better understand polyadenylation in Entamoeba histolytica, Giardia lamblia, and Cryptosporidium parvum, which represent leading causes of diarrhea worldwide, genomes were screened for orthologs of human factors. Results showed that Entamoeba histolytica and C. parvum have 16 and 12 proteins out of the 19 human proteins used as queries, respectively, while G. lamblia seems to have the smallest polyadenylation machinery with only six factors. Remarkably, CPSF30, CPSF73, CstF77, PABP2, and PAP, which were found in all parasites, could represent the core polyadenylation machinery. Multiple genes were detected for several proteins in Entamoeba, while gene redundancy is lower in Giardia and Cryptosporidium. Congruently with their relevance in the polyadenylation process, CPSF73 and PAP are present in all parasites, and CFIm25 is only missing in Giardia. They conserve the functional domains and predicted folding of human proteins, suggesting they may have the same roles in polyadenylation.
Subject(s)
Cleavage And Polyadenylation Specificity Factor/genetics , Cryptosporidium parvum/genetics , Entamoeba histolytica/genetics , Giardia lamblia/genetics , Intestines/parasitology , RNA, Messenger/genetics , Cleavage And Polyadenylation Specificity Factor/chemistry , Cleavage And Polyadenylation Specificity Factor/metabolism , Cryptosporidium parvum/metabolism , Databases, Genetic , Entamoeba histolytica/metabolism , Giardia lamblia/metabolism , Humans , Models, Molecular , Open Reading Frames , Poly A/chemistry , Protein Domains , Protein Structure, Tertiary , Protozoan Proteins/chemistry , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , RNA, Messenger/chemistry , RNA, Protozoan/chemistry , RNA, Protozoan/genetics , Sequence Alignment , Sequence Analysis, ProteinABSTRACT
In trypanosomes transcription is polycistronic and individual mRNAs are generated by a trans-splicing/polyadenylation coupled reaction. We identified a divergent trypanosome FIP1-like, a factor required for mRNA 3' end formation from yeasts to human. Here we showed that it is a nuclear protein with a speckled distribution essential for trypanosome viability. A strong interaction was found between TcFIP1-like and TcCPSF30, a component of the polyadenylation complex. We determined the specific amino acids in each protein involved in the interaction. Significant differences were found between the trypanosome interaction surface and its human counterpart. Although CPSF30/FIP1 interaction is known in other organisms, this is the first report mapping the interaction surface at the amino acid level.