The hydrothermal imprint on life: did heat-shock proteins, metalloproteins and photosynthesis begin around hydrothermal vents?

Abstract Molecular evidence implies that the first living community existed around a hydrothermal system. From this setting, life may have colonized a wide variety of hydrothermal environments. These would have included hydrothermal systems on mid-ocean ridges, around komatiite plume volcanoes, and in a variety of shallow-water settings. Hydrothermal systems on ridge segments may have been crucial in providing habitats to sustain the first communities of life. The early hydrothermal heritage may now be deeply imprinted in all organic life. Biological processes that use essential metals, especially Fe (typically as 4Fe-4S), Mn, Zn, Cu, Mo, Mg, Se and Ni, may all have hydrothermal descent from reactions that first evolved on a natural hydrothermal metal sulphide substrate, and it is possible that the first supply of P, when life began, was also associated with volcanism. The heat-shock proteins and many important ‘housekeeping’ enzymes of the biosphere, such as urease, hydrogenase, and nitrogenase may all be of hydrothermal origin. Photosynthesis may have originated via infrared phototaxis developed at mid-ocean ridge hydrothermal systems. The modern biosphere may have grown out of bacterial processes originally evolved at mid-ocean ridges.