The Earth?s deep oceans are home to an enormous amount and diversity of living creatures, including ~90% of the microbes, which can experience pressures as high as 1000 times that on the surface. The protein machines responsible for critical life processes, such as transcription of the genetic code, must be adapted to function under such extreme and inhospitable conditions. The mechanisms of this adaptation remain a mystery. This project is aimed at understanding molecular mechanisms underlying the response and adaptation to high pressure of the transcription machinery of surface- and pressure-adapted microorganisms. Better knowledge of these mechanisms will provide insights into the evolution and even the origins of life on Earth, and enable new biotechnological advances in the food science industry, e.g., to improve the safety of pressure pasteurization. Graduate students and postdoctoral scholars involved in the project will be trained in multidisciplinary research skills, and have the opportunity to mentor undergraduates and high school students. All trainees will participate in a Research Coordination Network on Extreme Biology and Biophysics.
In the mesophile, Escherichia coli, and in the moderate piezophile, Photobacterium profundum SS9, the molecular basis of transcriptional response and adaptation to pressure involves the heat shock response system. High pressure induces a heat shock response in E. coli, and conversely, low pressure induces a heat shock response P. profundum SS9. The research will investigate pressure effects on promoter interactions of the transcriptional regulators of housekeeping and stress response RNA polymerase sigma factors, as well as the stability of the sigma factor proteins themselves. These responses will be characterized in P. profundum SS9 and a pressure-adapted strain of E. coli for comparative analysis. The ToxR/ToxS transcriptional regulator system, which is implicated in pressure regulation of the transcriptional program in P. profundum SS9, will also be examined. The research will involve direct observation and quantification of transcriptional protein properties and processes, using newly developed fluorescence microscopy techniques under pressure, and will employ stochastic modeling for deeper insights into the pressure sensitivity of specific biochemical steps in these processes. The project outcomes are expected to provide insights into evolutionary adaptation to high pressure environments on Earth and may help to mitigate problems caused by pressure resistant microorganisms in the food industry.
This project is jointly funded by the Genetic Mechanisms and Molecular Biophysics programs of the Molecular and Cellular Biosciences Division in the Biological Sciences Directorate, and the Biological Oceanography program of the Ocean Sciences Division in the Geosciences Directorate.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
