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ACT1-CUP1 Assays Determine the Substrate-Specific Sensitivities of Spliceosomal Mutants in Budding Yeast
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ACT1-CUP1 Assays Determine the Substrate-Specific Sensitivities of Spliceosomal Mutants in Budding Yeast

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CEF1/CDC5 alleles modulate transitions between catalytic conformations of the spliceosome

Charles C Query1, Maria M Konarska

  • 1Department of Cell Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA. charles.query@einstein.yu.edu

RNA (New York, N.Y.)
|March 13, 2012
PubMed

Insights

Investigating spliceosome function, researchers found that CEF1 gene mutations suppress splicing defects. These mutations stabilize the spliceosome during a critical transition, influencing alternative splicing in yeast.

Area of Science:

  • Molecular Biology
  • Genetics
  • Biochemistry

Background:

  • Spliceosome conformational changes are essential for pre-mRNA splicing.
  • A genetic screen identified mutations that suppress splicing defects occurring between the first and second catalytic steps.

Purpose of the Study:

  • To identify and characterize non-prp8 suppressors of second-step splicing defects.
  • To elucidate the role of CEF1 in spliceosome dynamics and pre-mRNA splicing.

Main Methods:

  • Genetic screening to identify suppressor mutations.
  • Analysis of yeast pre-mRNA splicing in various mutant strains.
  • Investigating genetic and functional interactions between different spliceosome components.

Main Results:

  • The strongest non-prp8 suppressors were identified as alleles of CEF1, a component of the NTC (Prp19 complex).
  • CEF1 alleles suppress second-step splicing defects caused by various mutations and can activate alternative 3' splice sites.
  • Genetic interactions between CEF1 and PRP8 suggest they modulate the same event in the first-to-second-step spliceosome transition, likely via stabilization of the second-step spliceosome.

Conclusions:

  • CEF1 alleles stabilize the second-step spliceosome, distinct from the stabilization of the first-step spliceosome by U6 snRNA alleles.
  • A myb-like domain of Cef1/CDC5 is implicated in modulating spliceosome conformational states.
  • Alterations in these events affect splice site usage, leading to alternative splicing-like patterns in yeast.

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