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Single molecule analysis reveals reversible and irreversible steps during spliceosome activation.

ABSTRACT: The spliceosome is a complex machine composed of small nuclear ribonucleoproteins (snRNPs) and accessory proteins that excises introns from pre-mRNAs. After assembly the spliceosome is activated for catalysis by rearrangement of subunits to form an active site. How this rearrangement is coordinated is not well-understood. During activation, U4 must be released to allow U6 conformational change, while Prp19 complex (NTC) recruitment is essential for stabilizing the active site. We used multi-wavelength colocalization single molecule spectroscopy to directly observe the key events in Saccharomyces cerevisiae spliceosome activation. Following binding of the U4/U6.U5 tri-snRNP, the spliceosome either reverses assembly by discarding tri-snRNP or proceeds to activation by irreversible U4 loss. The major pathway for NTC recruitment occurs after U4 release. ATP stimulates both the competing U4 release and tri-snRNP discard processes. The data reveal the activation mechanism and show that overall splicing efficiency may be maintained through repeated rounds of disassembly and tri-snRNP reassociation.

SUBMITTER: Hoskins AA

PROVIDER: S-EPMC4922858 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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Single molecule analysis reveals reversible and irreversible steps during spliceosome activation.

Hoskins Aaron A AA Rodgers Margaret L ML Friedman Larry J LJ Gelles Jeff J Moore Melissa J MJ

eLife 20160531

The spliceosome is a complex machine composed of small nuclear ribonucleoproteins (snRNPs) and accessory proteins that excises introns from pre-mRNAs. After assembly the spliceosome is activated for catalysis by rearrangement of subunits to form an active site. How this rearrangement is coordinated is not well-understood. During activation, U4 must be released to allow U6 conformational change, while Prp19 complex (NTC) recruitment is essential for stabilizing the active site. We used multi-wave ...[more]

PMID: 27244240

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Dataset Information

Single molecule analysis reveals reversible and irreversible steps during spliceosome activation.

Publications

Single molecule analysis reveals reversible and irreversible steps during spliceosome activation.

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