Compared to us, the bacteria and algae are much less spoiled creatures. They exist without special complaints in the frozen Antarctica or in boiling water springs, without any ability to regulate body heat, and certainly without any technological means. How do they manage to thrive in environments with extreme temperatures?
Hamsin in control
The heat creeps slowly
Every day like Shabbat is stretched
Hamsin in control
Lyrics and music: Naomi Shemer
Original performance: Ili Gorlitsky and the Central Command Band
Text:
People do not function well in high heat stress, or when they are too cold. It is difficult to describe modern life without a burning fireplace, a hot bottle, coats, fans and air conditioners. Compared to us, the bacteria and algae are much less spoiled creatures. They exist without special complaints in the frozen Antarctica or in boiling water springs, without any ability to regulate body heat, and certainly without any technological means. How do they manage to thrive in environments with extreme temperatures? If we find the answer to this question we can, perhaps, improve the ability of agricultural crops to deal with hot and cold conditions, optimize industrial processes and find solutions to various environmental problems. These are exactly the questions that are at the center of the activity of a multidisciplinary scientific team headed by Prof. Avigdor Scharts from the Department of Plant Sciences at the Weizmann Institute of Science. Together with the team, which included the research students Oksana Schlick-Kerner, Ilan Samish and Hader Kels, and the post-doctoral researchers David Kafatan, Neta Holland and Maruti Say, Prof. Shertz tried to decipher the mechanisms that allow different creatures to live and thrive in an environment characterized by a wide range of temperatures. Or, as the scientists put it: how enzymatic systems with very similar structure and properties manage to function with similar efficiency under extremely different temperature conditions.
The researchers examined different species of bacteria that carry out photosynthesis (production of food substances - sugars - with the help of solar energy). They focused on one of the key steps of the process (the transfer of an electron between two molecules located on a protein "reaction center"), and compared the rate of this reaction in two species of bacteria, while gradually raising the ambient temperature.
To their surprise, the researchers discovered that the reaction does not obey the popular belief that the rate of any enzymatic reaction increases exponentially with increasing temperature. In fact, it became clear to them that the reaction rate peaked exactly in the temperature range where the bacteria "like" to exist. This rate remained unchanged even as the ambient temperature continued to rise. In other words, the bacteria are not affected by the errors of the weather, but regulate the rate of their enzymatic activity according to the average temperature of the environment in which they live. In this way, they avoid both a dangerous reduction in activity as a result of the cooling of the environment, and a destructive overactivity as a result of the warming of the environment.
How do they do it? The scientists examined the protein reaction centers where a key step in the photosynthesis process takes place in bacteria that "like" moderate temperatures, and in bacteria that thrive in a very hot environment. The proteins of the two bacteria are almost identical, but the scientists were able to identify a tiny difference between them: two amino acids (the units that make up the proteins) in the protein of the bacteria that love the temperate environment, are different from those found at the same place on the protein sequence of the heat-loving bacteria. Long live the small difference. The scientists hypothesized that this difference allows the bacteria to adjust their rate of activity to the ambient temperature. Indeed, when the sequence of amino acids in the protein was changed using genetic engineering methods, the optimal activity range of the bacteria changed by about 10 degrees, similar to what happens in nature.
These findings, recently published in the online edition of the scientific journal Nature, may possibly help, in the future, in the development of plant varieties resistant to extreme temperatures, so that it would be possible, for example, to grow different food plants in desert areas. Additional applications may lead to the optimization of industrial processes involving enzymatic reactions. Prof. Shertz says that the ability to increase the rate of activity of the photosynthesis enzymes may possibly allow, in the future, to control the rate of photosynthesis and increase the absorption rate of carbon dioxide from the atmosphere - something that may allow a significant increase in the production of plant mass for the production of biofuel, and at the same time also reduce the greenhouse effect ".
