Despite its name, even the Dead Sea has signs of life. A team of Weizmann Institute researchers have uncovered the strategy that helps a microscopic alga proliferate in such surroundings, and their findings have unexpectedly shed light on the working of our kidneys.
Over the years, a number of Weizmann scientists have asked how molecules essential to life, such as proteins, have adapted to extreme environments. The proteins they investigated were isolated from halophilic (salt-loving) microorganisms in the Dead Sea. After determining the 3-D structures for several such proteins, researchers were able to explain how they not only cope with high salinities, but are actually "addicted" to them.
However, the alga Dunaliella salina is a different kind of organism; it can grow in any salinity, from the extremes of the Dead Sea to nearly fresh water. The uniquely salt-tolerant Dunaliella, which is commercially grown as a source of beta carotene, has been investigated for over 30 years, but the secrets of its exceptionally successful adaptation to salt remained unresolved.
In a paper published in the Proceedings of the [US] National Academy of Sciences, Prof. Ada Zamir and Dr. Lakshmanane Premkumar of the institute's biological chemistry department and Prof. Joel Sussman and Dr. Harry Greenblatt of the structural biology department revealed the structural basis of a remarkably salt-tolerant Dunaliella enzyme, a carbonic anhydrase, which may hold the key.
Comparisons with known carbon anhydrases from animal sources showed that the enzyme shares a basic plan with its distant relatives, but with a few obvious differences. The most striking of these is in the electrical charges on the protein surfaces: Charges on the salt-tolerant enzyme are uniformly negative (though not as intensely negative as those in halophilic proteins), while the surfaces of carbonic anhydrases that don?t tolerate salt have a negative/positive/neutral mix. This and other unique structural features may enable the algal carbonic anhydrase to be active in the presence of salt, although not dependent on it.
In a surprise twist, the researchers discovered that one other known carbonic anhydrase - found in mouse kidneys - had a similar salt-tolerant construction. Pondering why a structure conferring salt tolerance should evolve once in a Dead Sea organism and once in a mouse led the researchers to some new insights into kidney physiology. The researchers hope that the knowledge gleaned might provide the basis for drugs that could target enzymes based on their salt tolerance.
GOOD FELLOW
A senior University of Haifa professor has been named a fellow of the prestigious European Coordinating Committee for Artificial Intelligence (ECCAI), the umbrella organization of all European AI societies. Professor Martin Golumbic, founding director of the Caesarea Edmond Benjamin de Rothschild Foundation Institute for Interdisciplinary Applications of Computer Science, is the first Israeli researcher to be so honored. There are some 80 international scholars in the ECCAI who have made substantial scientific contributions in the field of artificial intelligence, an interdisciplinary field spanning computer science and cognition. Golumbic, who immigrated from the US in 1982, was cited by ECCAI past president Prof. Oliviero Stock of Italy for his contribution, "like few others," to the development of fundamental research in AI. The formal ceremony was held on August 1 in Edinburgh during the International Joint Conference on Artificial Intelligence.
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