Alba-domain proteins of Trypanosoma brucei are cytoplasmic RNA-binding proteins that interact with the translation machinery.

摘要: Trypanosoma brucei and related pathogens transcribe most genes as polycistronic arrays that are subsequently processed into monocistronic mRNAs. Expression is frequently regulated post-transcriptionally by cis-acting elements in the untranslated regions (UTRs). GPEET EP procyclins major surface proteins of procyclic (insect midgut) forms T. brucei. Three regulatory common to 3' UTRs both mRNAs regulate mRNA turnover translation. The glycerol-responsive element (GRE) unique UTR regulates its expression independently from EP. A synthetic RNA encompassing GRE showed robust sequence-specific interactions with cytoplasmic electromobility shift assays. This, combined column chromatography, led identification 3 Alba-domain proteins. RNAi against Alba3 caused a growth phenotype reduced levels Alba1 Alba2 proteins, indicative between family members. Tandem-affinity purification co-immunoprecipitation verified these also identified Alba4 sub-stoichiometric amounts. Alba recruited starvation granules together poly(A) RNA. Concomitant depletion all four specifically translation reporter transcript flanked UTR. Pulldown tagged confirmed binding ribosomal protein P0 and, case Alba3, cap-binding eIF4E4. In addition, partially cosediment polyribosomes sucrose gradients. seem have exhibited great functional plasticity course evolution. First DNA-binding Archaea, then association nuclear RNase MRP/P yeast mammalian cells, they were recently described components translationally silent complex containing stage-regulated Plasmodium. Our results consistent stage-specific regulation trypanosomes, but likely context initiation.