Mon, 12/05/2022 - 12:40pm Athens Abigail Johnson Marine Sciences University of Georgia Seminars Please join us on Monday December 5 at 12:40 pm for the UGA Department of Marine Sciences seminar. Dr. Abbie Johnson, a postdoctoral researcher in our department, will present her work on Deep Biosphere Microbial Protein Interaction with Clathrates. If anyone would like to meet with the speaker after the talk, please email Dr. Joye to set up a meeting (mandyjoye@gmail.com). Abstract: Clathrate hydrates – cages of water molecules that entrap guest gas molecules – are found globally in subsurface sediments along continental margins and under permafrost. Clathrates store gigatons of methane, a potent greenhouse gas; therefore, it is crucial to have a thorough understanding of the controls on their stability, especially with a changing climate. A sudden shift in clathrate stability boundaries could trigger a massive release of methane, creating positive feedback, further warming our planet. Antifreeze proteins found in ice-dwelling organisms have been tested for their ability to bind and inhibit clathrate growth to avoid explosive clathrates in natural gas pipelines. Finding an effective, environmentally friendly compound, like proteins, would help to prevent tragic explosions and oil spills. I hypothesized that native, bacterial clathrate-bearing sediment proteins (clathrate-binding proteins, CBPs) would function similarly to antifreeze proteins by binding and altering the clathrate structure and stability boundaries. To test this hypothesis, I tested the effect of recombinantly expressed CBPs on different types of clathrate: tetrahydrofuran (THF) clathrate and methane clathrate. Tetrahydrofuran (THF) clathrate is a low-pressure, liquid clathrate, which is used as an analog for natural gas clathrate. To test the effect of CBPs on THF clathrate, I engineered a temperature- controlled case and a drainage-capable beaker to form THF clathrate crystals in the presence of CBPs. With no additives, the nucleated THF solution formed a single, octahedral THF clathrate crystal. In the presence of antifreeze proteins and CBPs, flat, hexagonal crystals formed (Johnson et al., 2020). I also tested CBPs fused to green fluorescent protein; the surface of THF clathrate glowed green, indicating that CBPs bind clathrates similarly to antifreeze proteins. I tested the effect of CBPs on methane clathrate stability boundaries by forming a shell of methane clathrate on a treatment droplet in a high-pressure cell we engineered (Johnson et al., 2021). In addition to climate change, this research has implications for searching for life on other planetary bodies that may contain methane clathrate, such as Mars, Titan, and Pluto. The Zoom link for those of you joining from your computers will be https://zoom.us/j/97461643834. Marine Sciences Room 239 and the Skidaway Auditorium will have a live feed of the talk. The room will be open at 12:20 pm, and the talk will begin at 12:40 pm. Our complete schedule of talks this semester is listed on the calendar: https://bit.ly/UGA-MarSci-Sched-Share
