Some Like It (Very) Hot! …
HIV and SARS are household words because they cause important diseases. However, most viruses are not disease causing; and they have played a central role in our understanding of modern biology… from the discovery of DNA to the role of viruses in driving evolution! Continuing in this tradition, an interdisciplinary team of TBI scientists are focused on the discovery and characterization of novel viruses from high temperature acidic environments found in Yellowstone National Park. Detailed molecular analysis of these viruses is leading to new insights into the unique biochemical adaptations required for life at high temperatures. The development of techniques used to detect viruses in geothermal environments can be adapted to other extreme environments such as on non-earth based bodies. Why look for viruses in Yellowstone’s high temperature environments? The study of viruses is an important tool for understanding how biological environments function. Viruses are ubiquitous with life and are molecular parasites within the cells they occupy, biochemically mimicking the cellular environment in which they replicate.
Because viruses have no “universal gene” for use as a molecular fish hook, TBI scientists had to develop techniques to identify viruses that have potentially never been seen before. The perfecting of these techniques made it evident that diverse viruses are abundant in Yellowstone’s geothermal features.TBI virologist, Dr. Mark Young, along with several collaborators, are the first scientists to systematically look for viruses in Yellowstone high temperature environments greater than 80° C (176° F) with pH of 3 or lower, essentially the equivalent of looking for viruses replicating in boiling acid! To date, the viruses discovered by Young and his collaborators are completely novel and not related to viruses found at ‘normal’ temperatures.The initial molecular characterization of these newly-discovered viruses has revealed characteristics not previously seen in any other virus. For example, the high resolution structure of one virus particle reveals an intricate surface architecture with propeller-like protrusions extending away from the surface. The sequence of its viral DNA genome revealed genes not related to any other known genes in biology. These are exciting results as they strongly suggest that the function of these new genes is related to unique requirements for life at high temperatures. These findings have been published in the Proceeding of the National Academy and the Journal of Virology.Where are we going next? An even more detailed analysis of these viruses is being pursued. TBI member Martin Lawrence is using the tools of x-ray crystallography to perform structural analysis at the atomic resolution of the viral gene products. Simultaneously, a genetic approach is being pursued by TBI faculty Mark Young and Trevor Douglas to unravel viral gene function. One long-term goal is to determine how changes in the geochemistry of particular Yellowstone thermal features alter the virus population structure within that feature. We are also comparing the newly discovered Yellowstone viruses with viruses found in other thermal features worldwide. And of course, we continue to search for new viruses from Yellowstone’s extreme environments. There is little doubt that Yellowstone’s thermal features will continue to provide a rich source for scientific inquiries into life in extreme environments.