Gcn4 misregulation reveals a direct role for the evolutionary conserved EKC/KEOPS in the t 6A modification of tRNAs

Marie Claire Daugeron, Tineke L. Lenstra, Martina Frizzarin, Basma El Yacoubi, Xipeng Liu, Agns Baudin-Baillieu, Philip Lijnzaad, Laurence Decourty, Cosmin Saveanu, Alain Jacquier, Frank C.P. Holstege, Valérie De Crécy-Lagard, Herman Van Tilbeurgh, Domenico Libri

Onderzoeksoutput: Bijdrage aan tijdschriftArtikelpeer review

67 Citaten (Scopus)

Samenvatting

The EKC/KEOPS complex is universally conserved in Archaea and Eukarya and has been implicated in several cellular processes, including transcription, telomere homeostasis and genomic instability. However, the molecular function of the complex has remained elusive so far. We analyzed the transcriptome of EKC/KEOPS mutants and observed a specific profile that is highly enriched in targets of the Gcn4p transcriptional activator. GCN4 expression was found to be activated at the translational level in mutants via the defective recognition of the inhibitory upstream ORFs (uORFs) present in its leader. We show that EKC/KEOPS mutants are defective for the N6-threonylcarbamoyl adenosine modification at position 37 (t 6A37) of tRNAs decoding ANN codons, which affects initiation at the inhibitory uORFs and provokes Gcn4 de-repression. Structural modeling reveals similarities between Kae1 and bacterial enzymes involved in carbamoylation reactions analogous to t 6A37 formation, supporting a direct role for the EKC in tRNA modification. These findings are further supported by strong genetic interactions of EKC mutants with a translation initiation factor and with threonine biosynthesis genes. Overall, our data provide a novel twist to understanding the primary function of the EKC/KEOPS and its impact on several essential cellular functions like transcription and telomere homeostasis.

Originele taal-2Engels
Pagina's (van-tot)6148-6160
Aantal pagina's13
TijdschriftNucleic Acids Research
Volume39
Nummer van het tijdschrift14
DOI's
StatusGepubliceerd - aug. 2011
Extern gepubliceerdJa

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