2008 Volume 2 Issue 1 Pages 45-53
Studies of pressure-adapted (piezophilic) protein have lagged behind the investigation of other extremophilic proteins, however the recent characterization of proteins from deep-sea organisms has substantially accelerated the field. For example studies on piezophilic bacterium Shewanella violacea strain DSS12, which was isolated from a sediment sample collected at the Ryukyu Trench (depth: 5,110 m), has elucidated the molecular basis for gene and protein regulation at different pressure conditions. Recent experiments on dihydrofolate reductases, isopropylmalate dehydrogenases, and RNA polymerase subunits from the strain DSS12 have contributed to our understanding of protein adaptation to high pressure. These studies have also complemented previous work that had investigated the effect of pressure on the activity and stability of “normal”, unadapted proteins. Together this research has lead to the conclusion that volume changes due to the hydration effects of exposed side chains and large internal cavities drive protein unfolding under high pressure. The tight packing of internal hydrophobic core and the replacement of surface loops with β-structures have also been identified as major structural strategies that confer high-pressure adaptation to piezophilic proteins by reducing their compressibility.
