All life on earth contains DNA, which is used to store biological information. Organisms compact their DNA in order for it to fit inside their cell(s). Specialized proteins, which are referred to... Show moreAll life on earth contains DNA, which is used to store biological information. Organisms compact their DNA in order for it to fit inside their cell(s). Specialized proteins, which are referred to as nucleoid-associated proteins (NAPs), help organize the DNA to keep it compact but accessible for transcription. These NAPs often function as DNA benders, bridgers and wrappers. In most eukaryotic and archaeal species, histones are important NAPs that are able to bend or wrap the DNA duplex around its core. In this thesis, the histones from archaea are described in terms of their interaction with DNA. We describe archaeal histones on a molecular level and analyze their primary structure. We also characterize recombinant expressed archaeal histones using single molecule techniques such as tethered particle motion and magnetic tweezers. Experiments using these techniques show that some archaeal histones form a rod-shaped structure together with DNA in solution. This hypernucleosome strongly compacts DNA. Furthermore, we discuss the impact of hypernucleosome formation on transcription regulation in archaea. Show less
Understanding of chromatin organization and compaction in Archaea is currently limited. The genome of several megabasepairs long is folded by a set of small chromatin proteins to fit into the... Show moreUnderstanding of chromatin organization and compaction in Archaea is currently limited. The genome of several megabasepairs long is folded by a set of small chromatin proteins to fit into the micron-sized cell. A first step in understanding archaeal chromatin organization is to study the action of individual chromatin proteins on DNA. Characterization of the architectural properties of these proteins is essential to understand how they shape and modulate the archaeal genome. This thesis describes the biophysical characterization of several chromatin proteins from the crenarchaeal model organism Sulfolobus solfataricus: Cren7, Sul7, Alba and Sso10a. The architectural properties of these proteins resemble those of their bacterial counterparts, suggesting that they could play a similar role in chromatin organization and global gene regulation. Show less
