SF3B1/Hsh155 HEAT motif mutations affect interaction with the spliceosomal ATPase Prp5, resulting in altered branch site selectivity in pre-mRNA splicing

Qing Tang, Susana Rodriguez-Santiago, Jing Wang, Jia Pu, Andrea Yuste, Varun Gupta, Alberto Moldón, Yong Zhen Xu, Charles C. Query

Research output: Contribution to journalArticle

30 Scopus citations


Mutations in the U2 snRNP component SF3B1 are prominent in myelodysplastic syndromes (MDSs) and other cancers and have been shown recently to alter branch site (BS) or 3′splice site selection in splicing. However, the molecular mechanism of altered splicing is not known. We show here that hsh155 mutant alleles in Saccharomyces cerevisiae, counterparts of SF3B1 mutations frequently found in cancers, specifically change splicing of suboptimal BS pre-mRNA substrates. We found that Hsh155p interacts directly with Prp5p, the first ATPase that acts during spliceosome assembly, and localized the interacting regions to HEAT (Huntingtin, EF3, PP2A, and TOR1) motifs in SF3B1 associated with disease mutations. Furthermore, we show that mutations in these motifs from both human disease and yeast genetic screens alter the physical interaction with Prp5p, alter branch region specification, and phenocopy mutations in Prp5p. These and other data demonstrate that mutations in Hsh155p and Prp5p alter splicing because they change the direct physical interaction between Hsh155p and Prp5p. This altered physical interaction results in altered loading (i.e., “fidelity”) of the BS–U2 duplex into the SF3B complex during prespliceosome formation. These results provide a mechanistic framework to explain the consequences of intron recognition and splicing of SF3B1 mutations found in disease.

Original languageEnglish (US)
Pages (from-to)2710-2723
Number of pages14
JournalGenes and Development
Issue number24
StatePublished - Dec 15 2016



  • Disease mutation
  • HEAT motif
  • Pre-mRNA splicing fidelity
  • Prp5
  • SF3B1/Hsh155

ASJC Scopus subject areas

  • Genetics
  • Developmental Biology

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