Living with Salt


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Life thrives in all sorts of hostile environments, including the extreme salinity of the Dead Sea. For over 30 years, Weizmann Institute scientists have been investigating how Dunaliella salina, a microscopic, plant-like alga, is able to proliferate in such inhospitable surroundings. As an offshoot of these and other studies, Dunaliella is today commercially grown as a source of natural beta carotene. Now Institute scientists have unraveled one of the secrets of the alga’s exceptionally successful adaptation to salt that, unexpectedly, might also shed light on the working of our own kidneys.
Prof. Ada Zamir and Dr. Lakshmanane Premkumar of the Biological Chemistry Department and Prof. Joel Sussman and Dr. Harry Greenblatt of the Structural Biology Department focused on an exceptionally salt-tolerant Dunaliella enzyme, a carbonic anhydrase. They showed that although the Dunaliella enzyme shares a basic plan with salt-intolerant carbon anhydrases from animal sources, it has unique structural features that enable it to remain functional in any degree of salinity, from the extremes of the Dead Sea to nearly fresh water.
In a surprising twist, the researchers discovered that one other carbonic anhydrase – found in mouse kidneys – sported a similar, salt-tolerant structure. Since the mouse enzyme closely resembles that of humans, the researchers hope that their findings might provide the basis for designing new drugs that could target carbonic anhydrase enzymes on the basis of their salt tolerance.

Human (left), Dunaliella (center) and mouse (right) enzymes



Prof. Joel Sussman’s research is supported by the Helen and Milton A. Kimmelman Center for Biomolecular Structure and Assembly; the Joseph and Ceil Mazer Center for Structural Biology; the Divadol Foundation; the Jean and Jula Goldwurm Memorial Foundation; Sally Schnitzer; the Kalman and Ida Wolens Foundation; and the Wolfson Family Charitable Trust. Prof. Sussman is the incumbent of the Morton and Gladys Pickman Professorial Chair in Structural Biology.