Transcription in trypanosomes: a different means to the end

摘要: The recent publication of T. brucei genome has enabled a new wave molecular and genetic experiments, which have resulted in clearer picture the transcription machinery this organism. While trypanosomes possess most subunits common to three RNA polymerases typically found eukaryotes, number interesting differences exist, presumably reflecting their early divergence from eukaryote crown lineage. Most notably, absence many class-specific RNAP subunits, paucity general factors, suggests that intricate, varied, mechanisms for regulation transcript initiation higher eukaryotes arose after divergence. It appears Tritryp transcriptional apparatus may be primitive yet identified Eukarya, containing perhaps single shared set GTFs initiation. Indeed, I II promoters described share structural similarities with III type some protein-coding genes are transcribed by I. bidirectional II-mediated regions separating long polycistronic clusters trypanosomatids represent ancestral, less sequence-specific, mostly replaced other archetypal TATA-containing promoters. Unlike organisms where plays major role mRNA levels, control abundance occurs mainly at steps processing, stability degradation. This reliance on post-transcriptional gene expression explain relative dearth factors over-representation RNA-binding proteins trypanosome genome. Introduction In all living information encoded within DNA must into molecules either act directly, or translated proteins, carry out myriad processes involved cellular maintenance growth. multisubunit protein complexes recruited specific sites (promoters) each polymerase. process is differentially regulated according developmental proliferation state modification chromatin, as well recruitment mediator complexes. leads tran-