Katherine Harris, Brady Evans and Thomas Andros, Brigham Young University
Life Sciences
Metabolic diseases, such as obesity and diabetes, have become endemic and the need for better treatments is rising. Mutations in PAS kinase, a recently discovered sensory kinase, have been shown to cause Maturity Onset Diabetes of the Young (MODY) in humans (Semplici et al., 2011). In addition, PAS kinase deficient mice display many phenotypes related to diabetes including resistance to weight gain, insulin insensitivity and triglyceride accumulation in response to a high-fat diet (Hao et al., 2007). Despite its importance in metabolism, little is known about the regulation of PAS kinase. PAS kinase consists of a sensory PAS domain that binds to and inhibits a protein kinase domain (Amezcua et al, 2002). We are currently engaged in several yeast genetic screens which will allow identification of regions in the full length PAS kinase that are essential for activation or for binding its substrates. The first screen is based on the finding that PAS kinase overexpression rescues a temperature-sensitive mutation in Tor2, the tor2(ts). We have isolated both point mutations and truncations in PAS kinase which alleviate the tor2(ts), suggesting they are hyperactive alleles. These mutations identify novel regions involved in PAS kinase regulation. Our second screen uses the yeast 2-hybrid to select for both point mutations and truncations that increase the ability of PAS kinase to bind its substrates. These mutations will help identify key regions of PAS kinase utilized in substrate recognition. Finally, we have identified regions of PAS kinase that are well-conserved throughout evolution and will compare these regions with the regions affected by our mutations. This study will be the first reported mutagenic analysis of PAS kinase. Analysis of these specific genetic regions will help elucidate the molecular mechanisms involved in the regulation and function of PAS kinase, a key player in the development of metabolic disease.