DNA Segregation

Recent publication in Science from the Schumacher lab: Structures of archaeal DNA segregation machinery reveal bacterial and eukaryotic linkages

DNA segregation is one of the most fundamental processes in biology as it ensures that the replicated DNA is accurately transmitted to daughter cells during cell division. This process is essential for all organisms from bacteria to man. Although this process has been extensively studied in eukaryotes and bacterial plasmids, virtually nothing is known about DNA segregation in archaea, the third domain of life. Here, we describe the machinery and assembly mechanism of the archaeal Sulfolobus pNOB8 segregation system. We obtained structures for all the components of this system as well as the higher-order segregation assemblages. This system uses a ParA morot protein; an atypical ParB adaptor; and a centromere-binding component, AspA. AspA utilizes an unprecedented spreading mechanism to create a DNA superhelix onto which ParB assembles. This supercomplex links to the ParA motor, which contains a bacteria-like Walker motif. Strikingly, the C domain of ParB harbors structural similarity to CenpA, which dictates eukaryotic segregation. Thus, this archaeal system combines bacteria-like and eukarya-like components, which suggests the possible conservation of DNA segregation principles across the three domains of life.