Dr. Shiladitya DasSarma
University of Maryland School of Medicine
Institute of Marine and Environmental Technology
Friday, October 1, 2021
Host: Dr. Brian Cullum
“Extremophilic Enzyme Structure-Function Analysis and Buoyant Nanoparticles for Protein Display”
Our laboratory has long studied the molecular biology of Haloarchaea, extremophiles that grow in, and contain salt at concentrations near saturation, where limited water and high osmotic pressure can be major stress factors. Under such extreme conditions, DNA can flip into left-handed Z-DNA conformation and “ordinary” proteins may denature, aggregate and precipitate out of solution. Haloarchaea are remarkably polyextremophilic and frequently survive additional stressors, including low temperatures, high UV and ionizing radiation doses, and perchlorate ions, which it uses as a terminal electron acceptor for respiration in the absence of oxygen. Consequently, Haloarchaea are of interest as models for exploring the limits to biochemistry on Earth and possible survival of life elsewhere, such as on the planet Mars. In this seminar, after introducing the biochemical characteristics of Haloarchaea, I will highlight our current research, including: (1) Structure-function analysis of a highly negatively charged β-galactosidase enzyme adapted to both cold and hypersaline conditions, and capable of activity in organic solvents and perchlorates; and (2) Progress in characterizing and utilizing novel, buoyant protein nanoparticles called gas vesicles (GVNPs). These remarkable nanoparticles are used for cell buoyancy and I will share with you recent advances in understanding their architecture and developing the versatile platform for protein display and potential therapeutic applications. These studies expand our knowledge of the remarkable adaptive characteristics and wealth of uses of extremophiles growing near the limits to life on Earth.