title: Both catalytic steps of nuclear pre-mRNA splicing are reversible.
abstract: Nuclear pre-messenger RNA (pre-mRNA) splicing is an essential processing step for the production of mature mRNAs from most eukaryotic genes. Splicing is catalyzed by a large ribonucleoprotein complex, the spliceosome, which is composed of five small nuclear RNAs and more than 100 protein factors. Despite the complexity of the spliceosome, the chemistry of the splicing reaction is simple, consisting of two consecutive transesterification reactions. The presence of introns in spliceosomal RNAs of certain fungi has suggested that splicing may be reversible; however, this has never been demonstrated experimentally. By using affinity-purified spliceosomes, we have shown that both catalytic steps of splicing can be efficiently reversed under appropriate conditions. These results provide considerable insight into the catalytic flexibility of the spliceosome.
authors.affiliation: Institute of Microbiology and Immunology, National Yang-Ming University, Shih-Pai, Taipei, Taiwan, Republic of China.
authors.forename: Chi-Kang
authors.initials: CK
authors.lastname: Tseng
authors.forename: Soo-Chen
authors.initials: SC
authors.lastname: Cheng
mesh_terms: D002384:Catalysis; D002413:Cations, Divalent / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism; D004951:Esterification; D005091:Exons; D007438:Introns; D011189:Potassium Chloride / Q000378:metabolism; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012326:RNA Splicing; D000072260:RNA Splicing Factors; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D017381:Spliceosomes / Q000378:metabolism*
chemical_list: D002413:Cations, Divalent; D012322:RNA Precursors; D000072260:RNA Splicing Factors; D012331:RNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; D011189:Potassium Chloride; C067135:PRP22 protein, S cerevisiae; D053487:DEAD-box RNA Helicases