Life pushed to extremes: probing chromosome segregation in thermophilic Archaea

Archaea are remarkable objects of investigation due to their exquisitely unusual biological properties and macromolecules. They are widely disseminated in the most disparate environmental niches and present unique molecular adaptations to life pushed to extremes. Thermophilic archaea are important for fundamental studies on evolution and the origin of life: they can be considered as a ‘time capsule’ providing a unique glimpse of what life was like on Earth when this was a planet bursting with geological activities billions of years ago. In addition, the molecular adaptations to life in extreme environments make archaea interesting objects of investigation for biotechnology and synthetic biology applications.

Since their discovery almost four decades ago, there has been an escalation in knowledge, genome sequences and publications on this domain of life. However, the fundamental process of chromosome segregation remains a black box in this branch of the tree of life. We have recently published the identification and initial characterization of the first chromosome segregation system in archaea [Proc
Natl Acad Sci USA 2012, 109: 3754-3759]. This genome partition machine from the archaeon Sulfolobus solfataricus consists of two proteins named SegA and SegB and a cis-acting DNA region. Our biochemical and genetic data have indicated that the SegAB complex fulfils a crucial role in chromosome segregation and is the prototype of a DNA partition machine widespread across archaea. Sulfolobus represents an excellent model system to study chromosome partition, as it harbours one single chromosome copy, in contrast to other members of the archaea domain that are highly polyploid.

Now we want to widen our investigations to dissect an orthologous system in Sulfolobus acidocaldarius. Our key hypothesis is that the products of the identified genes are involved in chromosome segregation and constitute the core components of a genome partition system. This project will test the above hypothesis and explore the molecular mechanisms underpinning chromosome segregation in archaea by interlocking, multidisciplinary approaches ranging from genetics and biochemistry to cutting-edge super resolution microscopy and single-molecule experiments. The overarching aim is to produce a detailed, mechanistic map of a fundamental biological process in a group of organisms with a remarkable and yet underexploited potential for biotechnology and synthetic biology.