A forward genetic screen reveals essential and non-essential RNAi factors in Paramecium tetraurelia.
Bottom Line: Analyses of allelic diversity distinguish non-essential and essential genes and suggest that the screen is saturated for non-essential, single-copy genes.We show that non-essential genes are specifically involved in dsRNA-induced RNAi while essential ones are also involved in transgene-induced RNAi.One of the latter, the RNA-dependent RNA polymerase RDR2, is further shown to be required for all known types of siRNAs, as well as for sexual reproduction.
Affiliation: Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, Inserm, U1024, CNRS, UMR 8197, Paris F-75005, France email@example.com.Show MeSH
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Mentions: The remaining 26 lines were found to carry mutations in either of two new genes, for which one allele was initially identified by the whole-genome sequencing procedure. The missense mutation 1.8 (Figure 2; Supplementary Table S6) is located in the predicted gene PTETG9100013001 (ParameciumDB), encoding a protein of the nucleotidyl transferase family (also referred to as non-canonical polyA/U RNA polymerases (44)) (Figure 3A). It is related to the first described non-canonical polyA polymerase, Cid1 of S. pombe, as well as to S. pombe's Cid12 (Supplementary Figure S2), the first protein among others of that family shown to be involved in small RNA mediated silencing (45). The gene was therefore named CID1. Cid1 is closely related to Rdn2 of T. thermophila (Supplementary Figure S2; Figure 6A), which physically interacts with the RdRP Rdr1 in an ‘RdRC’ complex (46,47). CID1 is expressed at constant levels throughout the life cycle (Supplementary Figure S3).
Affiliation: Ecole Normale Supérieure, Institut de Biologie de l'ENS, IBENS, Inserm, U1024, CNRS, UMR 8197, Paris F-75005, France firstname.lastname@example.org.