An adequate response to a sudden temperature rise is crucial for cellular fitness and survival. While heat shock response is well-described in bacteria and eukaryotes, much less information is available for archaea, of which many characterized species are extremophiles thriving in habitats typified by large temperature gradients. Here, we describe known molecular aspects of archaeal heat shock proteins as key components of the protein homeostasis machinery and place this in a phylogenetic perspective with respect to bacterial and eukaryotic heat shock proteins. Particular emphasis is placed on structure-function details of the archaeal thermosome, which is a major element of the heat shock response and of which subunit composition is altered in response to temperature changes. In contrast to the structural response, it is largely unclear how archaeal cells sense temperature fluctuations and which molecular mechanisms underly the corresponding regulation. We frame this gap in knowledge by discussing emerging questions related to archaeal heat shock response and by proposing methodologies to address them. Additionally, as has been shown in bacteria and eukaryotes, heat shock stress response is expected to be relevant for the control of physiology and growth in various stress conditions beyond temperature stress. A better understanding of this essential cellular process in archaea will not only provide insights into the evolution of heat shock response and of its sensing and regulation, it will also inspire the development of biotechnological applications, both by enabling transfer of archaeal heat shock components to other biological systems as for the engineering of archaea as robust cell factories.
|Emerging Topics in Life Sciences
|Published - 22 Nov 2018