Friday, April 9, 2021

Covalent Probes for Aggregated Protein Imaging via Michael Addition

Wang Wan  Yanan Huang  Qiuxuan Xia  Yulong Bai  Yuwen Chen  Wenhan Jin  Mengdie Wang  Di Shen  Haochen Lyu  Yuqi Tang  Xuepeng Dong  Zhenming Gao  Qun Zhao  Lihua Zhang  Yu Liu

Angew. Chem. Int. Ed. 2021

Covalent chemical reactions to modify aggregated proteins are rare. Here, we reported covalent Michael addition can generally occur upon protein aggregation. Such reactivity was initially discovered by a bioinspired fluorescent color‐switch probe mimicking the photo‐conversion mechanism of Kaede fluorescent protein. This probe was dark with folded proteins but turned on red fluorescence (620 nm) when it non‐covalently bound to misfolded proteins. Supported by the biochemical and mass spectrometry results, the probe chemoselectively reacted with the reactive cysteines of aggregated proteins via covalent Michael addition and gradually switched to green fluorescence (515 nm) upon protein aggregation. Exploiting this Michael addition chemistry in the malachite green dye derivatives demonstrated its general applicability and chemical tunability, resulting in different fluorescence color‐switch responses. Our work may offer a new avenue to explore other chemical reactions upon protein aggregation and design covalent probes for imaging, chemical proteomics, and therapeutic purposes.

Chemical Specification of E3 Ubiquitin Ligase Engagement by Cysteine-Reactive Chemistry

Roman C. Sarott, Inchul You, Yen-Der Li, Sean T. Toenjes, Katherine A. Donovan, Pooreum Seo, Martha Ordonez, Woong Sub Byun, Muhammad Murtaz...