RESUMO
The SET and MYND Domain (SMYD) proteins comprise a unique family of multi-domain SET histone methyltransferases that are implicated in human cancer progression. Here we report an analysis of the crystal structure of the full length human SMYD3 in a complex with an analog of the S-adenosyl methionine (SAM) methyl donor cofactor. The structure revealed an overall compact architecture in which the "split-SET" domain adopts a canonical SET domain fold and closely assembles with a Zn-binding MYND domain and a C-terminal superhelical 9 α-helical bundle similar to that observed for the mouse SMYD1 structure. Together, these structurally interlocked domains impose a highly confined binding pocket for histone substrates, suggesting a regulated mechanism for its enzymatic activity. Our mutational and biochemical analyses confirm regulatory roles of the unique structural elements both inside and outside the core SET domain and establish a previously undetected preference for trimethylation of H4K20.
Assuntos
Histona-Lisina N-Metiltransferase/química , Histona-Lisina N-Metiltransferase/metabolismo , Adenosina/análogos & derivados , Adenosina/metabolismo , Sítios de Ligação , Histonas/metabolismo , Humanos , Masculino , Ligação Proteica , Estrutura Secundária de Proteína , Relação Estrutura-AtividadeRESUMO
A high-throughput chemiluminescence and ELISA-based biochemical assay to identify mTORC1/mTORC2 kinase inhibitors is described. These mTOR complexes were isolated from HeLa whole cell lysate using mTOR antibodies and in-well immunoprecipitation. The integrity and purity of the mTORC1 and mTORC2 immunocomplexes were confirmed by western blotting. Full-length recombinant 4E-BP1 was used as a substrate and the catalytic activity was measured by detection of p4E-BP1 [T37/46] by a chemiluminescence method. The performance of this assay that can be used to identify dual mTORC1 and mTORC2 kinase inhibitors in a high-throughput 384-well format is described.
