Dataset Information

Identification and characterization of nuclear non-canonical poly(A) polymerases from Trypanosoma brucei.

ABSTRACT: Regulation of nuclear genome expression in Trypanosoma brucei is critical for this protozoan parasite's successful transition between its vertebrate and invertebrate host environments. The canonical eukaryotic circuits such as modulation of transcription initiation, mRNA splicing and polyadenylation appear to be nearly non-existent in T. brucei suggesting that the transcriptome is primarily defined by mRNA turnover. Our previous work has highlighted sequence similarities between terminal RNA uridylyl transferases (TUTases) and non-canonical poly(A) polymerases, which are widely implicated in regulating nuclear, cytoplasmic and organellar RNA decay throughout the eukaryotic lineage. Here, we have continued characterization of TUTase-like proteins in T. brucei and identified two nuclear non-canonical poly(A) polymerases (ncPAPs). The 82kDa TbncPAP1 is essential for viability of procyclic and bloodstream forms of T. brucei. Similar to Trf4/5 proteins from budding yeast, TbncPAP1 requires protein cofactor(s) to exert poly(A) polymerase activity in vitro. The recombinant 54kDa TbncPAP2 showed a PAP activity as an individual polypeptide. Proteomic analysis of the TbncPAP1 interactions demonstrated its association with Mtr4 RNA helicase and several RNA binding proteins, including a potential ortholog of Air1p/2p proteins, which indicates the presence of a stable TRAMP-like complex in trypanosomes. Our findings suggest that TbncPAP1 may be a "quality control" nuclear PAP involved in targeting aberrant or anti-sense transcripts for degradation by the 3'-exosome. Such mechanisms are likely to play a major role in alleviating promiscuity of the transcriptional machinery.

SUBMITTER: Etheridge RD

PROVIDER: S-EPMC2852512 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Identification and characterization of nuclear non-canonical poly(A) polymerases from Trypanosoma brucei.

Etheridge Ronald D RD Clemens Daniel M DM Gershon Paul D PD Aphasizhev Ruslan R

Molecular and biochemical parasitology 20081125 1

Regulation of nuclear genome expression in Trypanosoma brucei is critical for this protozoan parasite's successful transition between its vertebrate and invertebrate host environments. The canonical eukaryotic circuits such as modulation of transcription initiation, mRNA splicing and polyadenylation appear to be nearly non-existent in T. brucei suggesting that the transcriptome is primarily defined by mRNA turnover. Our previous work has highlighted sequence similarities between terminal RNA uri ...[more]

PMID: 19070634

Similar Datasets

Project description:Trf4p and Trf5p are non-canonical poly(A) polymerases and are part of the heteromeric protein complexes TRAMP4 and TRAMP5 that promote the degradation of aberrant and short-lived RNA substrates by interacting with the nuclear exosome. To assess the level of functional redundancy between the paralogous Trf4 and Trf5 proteins and to investigate the role of the Trf4-dependent polyadenylation in vivo, we used DNA microarrays to compare gene expression of the wild-type yeast strain of S. cerevisiae with either that of trf4Delta or trf5Delta mutant strains or the trf4Delta mutant expressing the polyadenylation-defective Trf4(DADA) protein. We found little overlap between the sets of transcripts with altered expression in the trf4Delta or the trf5Delta mutants, suggesting that Trf4p and Trf5p target distinct groups of RNAs for degradation. Surprisingly, most RNAs the expression of which was altered by the trf4 deletion were restored to wild-type levels by overexpression of TRF4(DADA), showing that the polyadenylation activity of Trf4p is dispensable in vivo. Apart from previously reported Trf4p and Trf5p target RNAs, this analysis along with in vivo cross-linking and RNA immunopurification-chip experiments revealed that both the TRAMP4 and the TRAMP5 complexes stimulate the degradation of spliced-out introns via a mechanism that is independent of the polyadenylation activity of Trf4p. In addition, we show that disruption of trf4 causes severe shortening of telomeres suggesting that TRF4 functions in the maintenance of telomere length. Finally, our study demonstrates that TRF4, the exosome, and TRF5 participate in antisense RNA-mediated regulation of genes involved in phosphate metabolism. In conclusion, our results suggest that paralogous TRAMP complexes have distinct RNA selectivities with functional implications in RNA surveillance as well as other RNA-related processes. This indicates widespread and integrative functions of TRAMP complexes for the coordination of different gene expression regulatory processes.

Dataset Information

Identification and characterization of nuclear non-canonical poly(A) polymerases from Trypanosoma brucei.

Publications

Identification and characterization of nuclear non-canonical poly(A) polymerases from Trypanosoma brucei.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets