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

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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.