title: Isolation and characterization of the gene encoding yeast debranching enzyme.
abstract: Using a genetic screen aimed at identifying cellular factors involved in Ty1 transposition, we have identified a mutation in a host gene that reduces Ty1 transposition frequency. The mutant, dbr1, is also defective in the process of intron turnover. In dbr1 cells, excised introns derived from a variety of pre-mRNAs are remarkably stable and accumulate to levels exceeding that of the corresponding mRNA. The stable excised introns accumulate in the form of a lariat that is missing the linear sequences 3' of the branchpoint. The DBR1 gene has been isolated by complementation of the transposition phenotype. DBR1 is shown to encode debranching enzyme, an RNA processing activity that hydrolyzes the 2'-5' phosphodiester linkage at the branchpoint of excised intron lariats. In Saccharomyces cerevisiae, debranching enzyme plays a requisite role in the rapid turnover of excised introns, yet its function is not essential for viability.
authors.affiliation: Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
authors.forename: K B
authors.initials: KB
authors.lastname: Chapman
authors.forename: J D
authors.initials: JD
authors.lastname: Boeke
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004251:DNA Transposable Elements; D007438:Introns; D008969:Molecular Sequence Data; D009154:Mutation; D009690:Nucleic Acid Conformation; D016366:Open Reading Frames; D012316:RNA Nucleotidyltransferases / Q000235:genetics* / Q000378:metabolism; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism*; D012091:Repetitive Sequences, Nucleic Acid; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D012322:RNA Precursors; D012331:RNA, Fungal; D012316:RNA Nucleotidyltransferases; C048135:lariat debranching enzyme