Department of Bioengineering, School of Engineering, University of California Merced, Merced, California, USA.
Nat Commun. 2023 Dec 2;14(1):7957. doi: 10.1038/s41467-023-43691-4.
Pathogenic dsDNA prompts AIM2 assembly leading to the formation of the inflammasome, a multimeric complex that triggers the inflammatory response. The recognition of foreign dsDNA involves AIM2 self-assembly concomitant with dsDNA binding. However, we lack mechanistic and kinetic information on the formation and propagation of the assembly, which can shed light on innate immunity's time response and specificity. Combining optical traps and confocal fluorescence microscopy, we determine here the association and dissociation rates of the AIM2-DNA complex at the single molecule level. We identify distinct mechanisms for oligomer growth via the binding of incoming AIM2 molecules to adjacent dsDNA or direct interaction with bound AIM2 assemblies, resembling primary and secondary nucleation. Through these mechanisms, the size of AIM2 oligomers can increase fourfold in seconds. Finally, our data indicate that single AIM2 molecules do not diffuse/scan along the DNA, suggesting that oligomerization depends on stochastic encounters with DNA and/or DNA-bound AIM2.
致病双链 DNA 可引发 AIM2 组装，导致炎性体的形成，炎性体是一种多聚体复合物，可引发炎症反应。识别外来双链 DNA 需要 AIM2 自身组装，同时结合双链 DNA。然而，我们缺乏关于组装形成和传播的机制和动力学信息，这可以揭示先天免疫的时间反应和特异性。本研究将光学陷阱和共焦荧光显微镜相结合，在单分子水平上确定了 AIM2-DNA 复合物的结合和解离速率。我们通过将新的 AIM2 分子结合到相邻的双链 DNA 上或直接与结合的 AIM2 组装体相互作用，确定了寡聚体生长的不同机制，类似于初级和次级成核。通过这些机制，AIM2 寡聚体的大小可以在几秒钟内增加四倍。最后，我们的数据表明，单个 AIM2 分子不会沿 DNA 扩散/扫描，这表明寡聚化取决于与 DNA 和/或 DNA 结合的 AIM2 的随机相遇。
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