title: Genetic interactions of yeast NEP1 (EMG1), encoding an essential factor in ribosome biogenesis.
abstract: Nep1 methylates the hypermodified ψ1191 base of 18S rRNA and has an additional essential function during ribosome biogenesis. It is strongly conserved in eukaryotes and a point mutation causes the human Bowen-Conradi syndrome. To identify Δnep1-specific genetic interactions, viable deletions were screened genome-wide (SGA). Due to its essential function, we used, for the first time, query strain (Δnep1) with two additive suppressor conditions (mcRPS19B, nop6-1). Nep1 interacting genes correspond to ribosome biogenesis (RPS18A, RPS18B, RRP8, EFG1, UTP30), to ribosome quality control (UBP3, BRE5, UBP6) and to ribosome functional control (DOM34, no-go decay). Deletions in ribosome quality and functional control genes were synthetically sick with Δnep1. They cope with malfunctions and the respective deletions strengthen the Δnep1 growth deficiency. Except for Δrps18b, deletions in the identified ribosome biogenesis genes were synthetically lethal with Δnep1. While the synthetic lethalities of Δrrp8 and Δefg1 may result from additive defects, the Δutp30 deletion seems to be in close functional relationship. The Δutp30 deletion itself has no phenotype but it enforced all nep1-1(ts) mutant phenotypes. Furthermore, its overexpression partially restored the nep1-1(ts) growth deficiency. Our genetic and biochemical data suggest that Utp30 and Nep1 act together during pre-ribosomal complex formation and, along with Rps18, provide the surface for the Rps19 assembly to the 90S pre-ribosome.
authors.affiliation: Institute for Molecular Biosciences, Johann-Wolfgang Goethe University, Frankfurt am Main, Germany.
authors.forename: Valeska
authors.initials: V
authors.lastname: Schilling
authors.forename: Christian
authors.initials: C
authors.lastname: Peifer
authors.forename: Markus
authors.initials: M
authors.lastname: Buchhaupt
authors.forename: Stefanie
authors.initials: S
authors.lastname: Lamberth
authors.forename: Anatoli
authors.initials: A
authors.lastname: Lioutikov
authors.forename: Benjamin
authors.initials: B
authors.lastname: Rietschel
authors.forename: Peter
authors.initials: P
authors.lastname: Kötter
authors.forename: Karl-Dieter
authors.initials: KD
authors.lastname: Entian
mesh_terms: D004843:Epistasis, Genetic; D011485:Protein Binding; D012269:Ribosomal Proteins / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: C444457:EMG1 protein, S cerevisiae; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins