RESUMO
The epigenetic landscape of a cell frequently changes in response to fluctuations in nutrient levels, but the mechanistic link is not well understood. In fission yeast, the JmjC domain protein Epe1 is critical for maintaining the heterochromatin landscape. While loss of Epe1 results in heterochromatin expansion, overexpression of Epe1 leads to defective heterochromatin. Through a genetic screen, we found that mutations in genes of the cAMP signaling pathway suppress the heterochromatin defects associated with Epe1 overexpression. We further demonstrated that the activation of Pka1, the downstream effector of cAMP signaling, is required for the efficient translation of epe1+ mRNA to maintain Epe1 overexpression. Moreover, inactivation of the cAMP-signaling pathway, either through genetic mutations or glucose deprivation, leads to the reduction of endogenous Epe1 and corresponding heterochromatin changes. These results reveal the mechanism by which the cAMP signaling pathway regulates heterochromatin landscape in fission yeast.
Assuntos
Proteínas de Schizosaccharomyces pombe , Schizosaccharomyces , Heterocromatina/genética , Heterocromatina/metabolismo , Histonas/genética , Proteínas Nucleares/genética , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Proteínas de Schizosaccharomyces pombe/metabolismo , Transdução de Sinais/genéticaRESUMO
The ribosome translates the information stored in the genetic code into functional proteins. In this process messenger RNAs (mRNAs) serve as templates for the ribosome, ensuring that amino acids are linked together in the correct order. Chemical modifications to mRNA nucleosides have the potential to influence the rate and accuracy of protein synthesis. Here, we present an in vitro Escherichia coli translation system utilizing highly purified components to directly investigate the impact of mRNA modifications on the speed and accuracy of the ribosome. This system can be used to gain insights into how individual chemical modifications influence translation on the molecular level. While the fully reconstituted system described in this chapter requires a lengthy time investment to prepare experimental materials, it is highly verstaile and enables the systematic assessment of how single variables influence protein synthesis by the ribosome.
