Unexpected implications of STAT3 acetylation revealed by genetic encoding of acetyl-lysine
Unexpected implications of STAT3 acetylation revealed by genetic encoding of acetyl-lysine
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DOI：
10.1016/j.bbagen.2019.05.019
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发表时间：
2019-09-01
影响因子：
3
通讯作者：
Arbely, Eyal
中科院分区：
文献类型：
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作者：
Belo, Yael;Mielko, Zachery;Arbely, Eyal
信号转导和转录激活子3(STAT3)蛋白是通过磷酸化特定的酪氨酸残基(Tyr705)来响应各种细胞外信号而激活的。STAT3的活性也受到Lys685乙酰化的调节。然而，Lys685乙酰化影响STAT3转录活性的分子机制仍然不清楚。通过基因编码将乙酰赖氨酸共翻译结合到Lys685位，并将STAT3与ELK受体酪氨酸激酶共表达，我们能够表征位点特异的乙酰化以及同时乙酰化和磷酸化的STAT3。我们测量了乙酰化对Tyr705磷酸化和非磷酸化的STAT3的晶体结构、DNA结合亲和力和特异性的影响。此外，我们通过在活细菌中重组哺乳动物酶促脱乙酰基反应来监测乙酰化的Lys685的脱乙酰基。令人惊讶的是，我们发现乙酰化本身对STAT3的晶体结构和DNA结合亲和力或特异性没有影响，这意味着之前观察到的STAT3依赖乙酰化的转录活性涉及额外的细胞成分。此外，我们发现Tyr705-磷酸化保护Lys685在细菌中不去乙酰化，为观察到的STAT3活性和Lys685乙酰化之间的相关性提供了新的可能解释。
The signal transducer and activator of transcription 3 (STAT3) protein is activated by phosphorylation of a specific tyrosine residue (Tyr705) in response to various extracellular signals. STAT3 activity was also found to be regulated by acetylation of Lys685. However, the molecular mechanism by which Lys685 acetylation affects the transcriptional activity of STAT3 remains elusive. By genetically encoding the co-translational incorporation of acetyl-lysine into position Lys685 and co-expression of STAT3 with the Elk receptor tyrosine kinase, we were able to characterize site-specifically acetylated, and simultaneously acetylated and phosphorylated STAT3. We measured the effect of acetylation on the crystal structure, and DNA binding affinity and specificity of Tyr705-phosphorylated and non-phosphorylated STAT3. In addition, we monitored the deacetylation of acetylated Lys685 by reconstituting the mammalian enzymatic deacetylation reaction in live bacteria. Surprisingly, we found that acetylation, per se, had no effect on the crystal structure, and DNA binding affinity or specificity of STAT3, implying that the previously observed acetylation-dependent transcriptional activity of STAT3 involves an additional cellular component. In addition, we discovered that Tyr705-phosphorylation protects Lys685 from deacetylation in bacteria, providing a new possible explanation for the observed correlation between STAT3 activity and Lys685 acetylation.