title: The non-canonical CTD of RNAP-II is essential for productive RNA synthesis in Trypanosoma brucei.
abstract: The carboxy-terminal domain (CTD) of the largest subunit (RPB1) of RNA polymerase II (RNAP-II) is essential for gene expression in metazoa and yeast. The canonical CTD is characterized by heptapeptide repeats. Differential phosphorylation of canonical CTD orchestrates transcriptional and co-transcriptional maturation of mRNA and snRNA. Many organisms, including trypanosomes, lack a canonical CTD. In these organisms, the CTD is called a non-canonical CTD or pseudo-CTD (PsiCTD. In the African trypanosome, Trypanosoma brucei, the PsiCTD is approximately 285 amino acids long, rich in serines and prolines, and phosphorylated. We report that T. brucei RNAP-II lacking the entire PsiCTD or containing only a 95-amino-acid-long PsiCTD failed to support cell viability. In contrast, RNAP-II with a 186-amino-acid-long PsiCTD maintained cellular growth. RNAP-II with PsiCTD truncations resulted in abortive initiation of transcription. These data establish that non-canonical CTDs play an important role in gene expression.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Medicine and Dentistry-New Jersey Medical School, Newark, New Jersey, United States of America. A.Das-dasak@umdnj.edu
authors.forename: Anish
authors.initials: A
authors.lastname: Das
authors.forename: Vivian
authors.initials: V
authors.lastname: Bellofatto
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002470:Cell Survival; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D008954:Models, Biological; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D012313:RNA / Q000096:biosynthesis*; D012319:RNA Polymerase II / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000737:chemistry; D014346:Trypanosoma brucei brucei / Q000378:metabolism*
chemical_list: D012694:Serine; D012313:RNA; D012319:RNA Polymerase II