|Adaptation of Tubulin Protiens to Extreme Cold|
David J. Beaudoin Woods Hole Oceanographic Institution
Michael P. Cummings University of Maryland
Despite the prevalence of extremely cold environments on our earth, we understand very little about how organisms have adapted to live in them compared to what we know about how temperate organisms function. An area of study that we have become particularly interested in is the cold-adaptation of microtubules in protists. Microtubules are essential eukaryotic cellular components, and in temperate organisms, are unstable at low temperatures. This instability would be in conflict with life at low temperatures, but considering the relatively high level of diversity and abundance or protists in extremely cold environments, the organisms have obviously adapted. The results of several studies have led to the current understanding that the stability of cold-adapted microtubules is a property intrinsic to the tubulin subunits themselves. Yet overall, only a relatively small number of cold-adapted tubulin sequences have been examined, and because there are very few studies that compare cold-adapted sequences with ones from closely related mesophilic species, it has been difficult to determine whether there are conserved (common) types of changes or positions that correspond to cold-adaptation.
In our project, we will recover both alpha- and beta- tubulin sequences from closely related psychrophilic (from the Arctic and the Antarctic) and mesophilic protist species. Using novel statistical methods we will analyze tubulin sequences to identify shared sequence changes that potentially represent modifications for cold-stability of microtubules. Our study will not only determine whether there are specific sequence hallmarks of cold-adaptation in tubulin sequences, but it will also provide information on modifications that generally enhance interactions between protein subunits in psychrophiles.