Structural, biochemical and biophysical analysis of DisA and DAC-domain proteins

DNA完整性的维持是维持生命的一个重要因素，细胞通过各种DNA损伤传感器和检查点蛋白来监测这一点。虽然人类的检查点控制非常复杂，而且在机制上很难理解，但细菌系统有一个简单得多的系统，这是一个很有希望进行结构和机制分析的模型系统。我们已经解决了一个新发现的细菌DNA损伤传感器蛋白（DisA）的晶体结构，并发现它与DNA重组中间结构结合，从而阻止细胞进入孢子期。发现DisA具有以前未表征的二腺苷酸环化酶活性。由此产生的c-di-AMP与细菌生理学中众所周知的c-di-GMP有关。事实上，c-di-AMP之前没有被描述过，也没有已知的c-di-AMP调节蛋白，这为细菌信号传导开辟了一个全新的领域。C-di-AMP最近被证明在李斯特菌感染时触发细胞的干扰素反应，可能被STING蛋白识别，强调它在感染生物学和先天免疫中也很重要。我们的目的是分析DisA和其他蛋白合成c-di-AMP的机制，并确定可能的相互作用蛋白。作为一个长期目标，我们的目标是鉴定c-di-AMP信号通路中的蛋白质，以更全面地了解细胞中哪些过程可能受到调节。

The maintenance of DNA integrity is an important factor in sustainment of life, and cells monitor this by a variety of DNA damage sensors and checkpoint proteins. While humans have a very complex and mechanistically poorly understood checkpoint control, bacterial systems have a much simpler system that is a promising model system for structural and mechanistic analysis. We have solved the crystal-structure of a newly identified bacterial DNA-damage sensor protein (DisA) and discovered that it binds to DNA recombination intermediate structures, thereby preventing the cell from entering sporulation phase. DisA was found to have a previously uncharacterized di-adenylate cyclase enzymatic activity. The resulting c-di-AMP is related to the well know c-di-GMP in bacterial physiology. The fact that c-di-AMP has not been described before and no c-di-AMP-regulated proteins are known, opens up a completely new field in bacterial signaling. C-di-AMP has recently been shown to trigger interferon response of cells upon Listeria infection probably recognized by the STING protein, underlining that it is important also in infection biology and innate immunity. We aim to analyze the mechanism of DisA and other proteins synthesizing c-di-AMP and identify possible interacting proteins. As a long term goal we aim to identify proteins in the c-di-AMP signaling pathway to get a more complete picture of which processes may be regulated in the cell.