title: The RNA-dependent RNA polymerase, QDE-1, is a rate-limiting factor in post-transcriptional gene silencing in Neurospora crassa.
abstract: The RNA-dependent RNA polymerase (RdRP) qde-1 is an essential component of post-transcriptional gene silencing (PTGS), termed 'quelling' in the fungus Neurospora crassa. Here we show that the overexpression of QDE-1 results in a dramatic increase in the efficiency of quelling, with a concomitant net increase in the quantity of al-1 siRNAs. Moreover, in overexpressed strains there is a significant reduction in the number of transgenes required to induce quelling, and an increase in the phenotypic stability despite progressive loss of tandemly repeated transgenes, which normally determines reversion of a silenced phenotype to wild type. These data suggest that the activation and maintenance of silencing in Neurospora appear to rely both on the cellular amount of QDE-1 and the amount of transgenic copies producing RNA molecules that act as a substrate for the RdRP, implicating QDE-1 as a rate-limiting factor in PTGS.
authors.affiliation: Istituto Pasteur e Fondazione Cenci Bolognetti, Dipartimento di Biotecnologie Cellulari ed Ematologia, Sezione di Genetica Molecolare, Universitá di Roma La Sapienza, 00161 Roma, Italy.
authors.forename: Emma C
authors.initials: EC
authors.lastname: Forrest
authors.forename: Carlo
authors.initials: C
authors.lastname: Cogoni
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Macino
mesh_terms: D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D020868:Gene Silencing; D009492:Neurospora crassa / Q000201:enzymology* / Q000235:genetics*; D010641:Phenotype; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014170:Transformation, Genetic
chemical_list: D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; C119303:QDE1 protein, Neurospora crassa; D012324:RNA-Dependent RNA Polymerase