Enzymes feel the squeeze: biochemical adaptation to pressure in the deep sea

To the human observer, the deep sea is as extreme an environment as Earth has to offer. Below about 200 metres, there is no light from the surface, the water can be frigid (-2 to 5°C), oxygen and food are scarce, and the pressure is staggering. Of course, to the countless species that inhabit the deep sea, these conditions are not so extreme, and in a statistical sense, they fall fairly close to average, since the deep comprises the planet's largest habitat by volume. Despite its expanse, we know little about how life persists in an environment so different from our own. Only in the last half-century has technology emerged that allows us to collect and study live deep-sea animals. Diversity, Evolution and EcoPhysiology of Ctenophores (DEEPC, deepc.org, a US NSF-supported research effort) is opening a window on biochemistry in the deep, and specifically on its relationship to high pressure. By determining structural constraints on enzyme function under pressure, we aim to inform models focusing on deep-sea animal colonization, and to find general patterns of protein adaptation with possible applications in protein engineering and biocatalysis.