Collaborative Research: Analysis of Cold Tubulin Sequences and Their Implication for Cold-Adaptation of Microtubules

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ABSTRACTGast OPP-0324771CummingsOPP-0324378This is a collaborative proposal by Principal Investigators at the Marine Biological Laboratory and Woods Hole Oceanographic Institution. 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 interest to the Principal Investigators 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. The Principal Investigators will recover both a and b tubulin sequences from closely related psychrophilic (from the Arctic and the Antarctic) and mesophilic protist species. Using novel statistical methods, they will analyze tubulin sequences to identify shared sequence changes that potentially represent modifications for cold-stability of microtubules. This 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. This program will also begin an assessment of whether the protistan communities in the Arctic region are genetically and physiologically similar to those of the Antarctic. The question of endemic versus cosmopolitan microbial species distribution is a significant one for polar regions due to the important ecological impact these organisms have in extreme cold environments. They are essential components of the microbial food webs and are often the dominant primary producers. The molecular sequence data that the Principal Investigators will collect in this project (both ribosomal and tubulin) will be analyzed to compare the genetic relatedness of putatively similar protistan species/isolates from the two polar regions. There have been reports of similar protist species being observed and collected in both the Arctic and Antarctic, but only a few genetic comparisons have been accomplished and it remains a question as to how closely many of these organisms are actually related. Broader Impacts: Among the broader impacts of this project include the participation of the Principal Investigators in several courses and programs at WHOI and MBL associated with different levels of education, ranging from high school through college. Students involved in these courses and research programs, including those recruited from under-represented groups, will be exposed either directly (through participation in data analysis) or indirectly (through general information outreach) to this research. The dataset that they are generating, and the unique organisms that they are working with, will help to broaden the perspective that these students have regarding evolution, distribution and function of psychrophilic protists.