RESUMO
Small nucleolar RNA (snoRNA) are conserved and essential non-coding RNA that are transcribed by RNA Polymerase II (Pol II). Two snoRNA classes, formerly distinguished by their structure and ribonucleoprotein composition, act as guide RNA to target RNA such as ribosomal RNA, and thereby introduce specific modifications. We have studied the 5'end processing of individually transcribed snoRNA in S. cerevisiae to define their role in snoRNA biogenesis and functionality. Here we show that pre-snoRNA processing by the endonuclease Rnt1 occurs co-transcriptionally with removal of the m7G cap facilitating the formation of box C/D snoRNA. Failure of this process causes aberrant 3'end processing and mislocalization of snoRNA to the cytoplasm. Consequently, Rnt1-dependent 5'end processing of box C/D snoRNA is critical for snoRNA-dependent methylation of ribosomal RNA. Our results reveal that the 5'end processing of box C/D snoRNA defines their distinct pathway of maturation.
Assuntos
Núcleo Celular/metabolismo , RNA Fúngico/genética , RNA Nucleolar Pequeno/metabolismo , Saccharomyces cerevisiae/genética , Citoplasma/metabolismo , Metilação , Capuzes de RNA , Processamento Pós-Transcricional do RNA , RNA Fúngico/metabolismo , Ribonuclease III/genética , Ribonuclease III/metabolismo , Ribonucleoproteínas Nucleolares Pequenas/genética , Ribonucleoproteínas Nucleolares Pequenas/metabolismo , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismoRESUMO
m(7)GTP-Sepharose is routinely used for cap binding protein isolation. Here we present the synthesis of a new affinity resin containing a mononucleotide cap analog resistant to hydrolysis by DcpS. The resin has been designed in order to identify and purify Arabidopsis thaliana DcpS and other pyrophosphatases. The binding efficiency of the new resin to eIF4E protein was compared with standard m(7)GTP-Sepharose. The utility of non-hydrolysable resin was demonstrated on yeast extract.
