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The H/ACA complex disrupts triplex in hTR precursor to permit processing by RRP6 and PARN.

ABSTRACT: Human telomerase RNA (hTR) is transcribed as a precursor that is then posttranscriptionally modified and processed. A fraction of the transcripts is oligoadenylated by TRAMP and either processed into the mature hTR or degraded by the exosome. Here, we characterize the processing of 3' extended forms of varying length by PARN and RRP6. We show that tertiary RNA interactions unique to the longer transcripts favor RNA degradation, whereas H/ACA RNP assembly stimulates productive processing. Interestingly, the H/ACA complex actively promotes processing in addition to protecting the mature 3' end. Processing occurs in two steps with longer forms first being trimmed by RRP6 and shorter forms then being processed by PARN. These results reveal how RNA structure and RNP assembly affect the kinetics of processing and degradation and ultimately determine the amount of functional telomerase produced in cells.

SUBMITTER: Tseng CK

PROVIDER: S-EPMC6303318 | biostudies-literature | 2018 Dec

REPOSITORIES: biostudies-literature

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The H/ACA complex disrupts triplex in hTR precursor to permit processing by RRP6 and PARN.

Tseng Chi-Kang CK Wang Hui-Fang HF Schroeder Morgan R MR Baumann Peter P

Nature communications 20181221 1

Human telomerase RNA (hTR) is transcribed as a precursor that is then posttranscriptionally modified and processed. A fraction of the transcripts is oligoadenylated by TRAMP and either processed into the mature hTR or degraded by the exosome. Here, we characterize the processing of 3' extended forms of varying length by PARN and RRP6. We show that tertiary RNA interactions unique to the longer transcripts favor RNA degradation, whereas H/ACA RNP assembly stimulates productive processing. Interes ...[more]

PMID: 30575725

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The H/ACA complex disrupts triplex in hTR precursor to permit processing by RRP6 and PARN

Project description:Human telomerase RNA (hTR) is transcribed as a precursor that is then posttranscriptionally modified and processed. A fraction of the transcripts is oligoadenylated by TRAMP and either processed into the mature hTR or degraded by the exosome. Here, we characterize the processing of 3’ extended forms of varying length by PARN and RRP6. We show that tertiary RNA interactions unique to the longer precursor forms favor RNA degradation, whereas H/ACA RNP assembly stimulates productive processing. Interestingly, the H/ACA complex actively promotes processing in addition to protecting the mature 3’ end. Processing occurs in two steps with longer forms being trimmed by RRP6 and shorter forms being preferentially processed by PARN. These results reveal how RNA structure and RNP assembly affect the kinetics of processing and degradation and ultimately determine the amount of functional telomerase produced in cells.

2018-12-26 | GSE111081 | GEO

The H/ACA complex disrupts triplex in hTR precursor to permit processing by RRP6 and PARN

Project description:The H/ACA complex disrupts triplex in hTR precursor to permit processing by RRP6 and PARN

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Regulation of amyloid precursor protein processing by the Beclin 1 complex.

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TRAMP complex enhances RNA degradation by the nuclear exosome component Rrp6.

Project description:The RNA-processing exosome contains ribonucleases that degrade aberrant RNAs in archael and eukaryotic cells. In Saccharomyces cerevisiae, the nuclear/nucleolar 3'-5' exoribonuclease Rrp6 distinguishes the nuclear exosome from the cytoplasmic exosome. In vivo, the TRAMP complex enhances the ability of the nuclear exosome to destroy some aberrant RNAs. Previous reports showed that purified TRAMP enhanced RNA degradation by the nuclear exosome in vitro. However, the exoribonucleolytic component(s) of the nuclear exosome enhanced by TRAMP remain unidentified. We show that TRAMP does not significantly enhance RNA degradation by purified exosomes lacking Rrp6 in vitro, suggesting that TRAMP activation experiments with nuclear exosome preparations reflect, in part, effects on the activity of Rrp6. Consistent with this, we show that incubation of purified TRAMP with recombinant Rrp6 results in a 10-fold enhancement of the rate of RNA degradation. This increased activity results from enhancement of the hydrolytic activity of Rrp6 because TRAMP cannot enhance the activity of an Rrp6 mutant lacking a key amino acid side chain in its active site. We observed no ATP or polyadenylation dependence for the enhancement of Rrp6 activity by TRAMP, suggesting that neither the poly(A) polymerase activity of Trf4 nor the helicase activity of Mtr4 plays a role in the enhancement. These findings identify TRAMP as an exosome-independent enhancer of Rrp6 activity.

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