RESUMO
Using the amber suppression approach, Nϵ -(4-azidobenzoxycarbonyl)-δ,ϵ-dehydrolysine, an allysine precursor is genetically encoded in E. coli. Its genetic incorporation followed by two sequential biocompatible reactions allows convenient synthesis of proteins with site-specific lysine dimethylation. Using this approach, dimethyl-histone H3 and p53 proteins have been synthesized and used to probe functions of epigenetic enzymes including histone demethylase LSD1 and histone acetyltransferase Tip60. We confirmed that LSD1 is catalytically active toward H3K4me2 and H3K9me2 but inert toward H3K36me2, and methylation at p53 K372 directly activates Tip60 for its catalyzed acetylation at p53 K120.
Assuntos
Ácido 2-Aminoadípico/análogos & derivados , Escherichia coli/genética , Lisina/análogos & derivados , Mutagênese Sítio-Dirigida/métodos , Ácido 2-Aminoadípico/genética , Código Genético , Histonas/química , Histonas/genética , Humanos , Lisina/química , Lisina/genética , Metilação , Modelos Moleculares , Processamento de Proteína Pós-Traducional , Proteína Supressora de Tumor p53/química , Proteína Supressora de Tumor p53/genéticaRESUMO
Lysine acetylation serves as an epigenetic marker for myriad cellular processes, such as signaling, differentiation, DNA repair, angiogenesis, and the like. Sirtuin 1 (SIRT1) and sirtuin 2 (SIRT2) are NAD(+)-dependent histone deacetylases that operate as post-translational regulators for the deacetylation of acetyllysine. Here, we discuss the ability for SIRT1 and SIRT2 to deacetylate monoacetylated histone H3 on two separate architectures-the peptide and the nucleosome. In addition, we analyze the site-specificity of SIRT1 and SIRT2 on 10 different monoacetylated histone H3 nucleosomes. By utilizing a rapid screening array, SIRT1 and SIRT2 were found to demonstrate heightened enzymatic activity when incubated with nucleosomal substrates over their peptide counterparts. These two enzymes displayed little site-specificity among the acetyl-nucleosomes screened, contrary to previous expectations, as well. The implication of the overall nonspecificity of SIRT1 and SIRT2 on the nucleosome suggests that these sirtuin enzymes have an adaptive nature, harnessing an ability to respond to various cellular situations, rather than an enzyme specifically designed for a particular task or function.