Regulatory Roles in Photosynthesis of Unsaturated Fatty Acids in Membrane Lipids
The diversity of lipids in thylakoid membranes and their unique characteristics, in addition to their specific orientation in these membranes, strongly suggest that they play specific and important roles in the thylakoid membrane. In the chloroplasts of plants and algae, as well as in cyanobacterial cells, most of the photosyn-thetic machinery is embedded in thylakoid membranes, which are composed of proteins, lipids and pigments. Alterations in the extent of unsaturation of fatty acids in membrane lipids are expected to affect the physical characteristics of the membranes and, consequently, the activities of the photosynthetic machinery. The availability of entire genome sequences and an understanding of the functions of the individual genes for fatty acid desaturases in cyanobacteria led to the successful site-directed mutagenesis of such genes that reduced the extent of unsaturation of fatty acids in membrane lipids in a step-wise manner and, also, to the genetic transformation of cyanobacterial cells and whole plants that increased the extent of unsaturation of fatty acids in lipids of thylakoid membranes. Characterization of the photosynthetic properties of the transformed cyanobacteria and higher plants revealed that polyunsaturated fatty acids are essential for protection of the photosynthetic machinery against environmental stresses, such as strong light, salt stress, and high and low temperatures. Moreover, the available evidence suggests that the unsaturation of fatty acids enhances the repair of the photosystem II complex that has been damaged by strong light under stress conditions.
KeywordsSalt Stress Thylakoid Membrane Monounsaturated Fatty Acid Fatty Acid Desaturases Photosynthetic Machinery
Fourier transform infrared
- PS I
- PS II
Fatty acid in which X and Y indicate numbers of carbon atoms and double bonds, respectively, and Z in parenthesis indicates the position of double bond as counted from the carboxyl terminus of the fatty-acyl chain.
This work was supported, in part, by the Cooperative Research Program on the Stress Tolerance of Plants of the National Institute for Basic Biology to Norio Murata, and by grants from the Russian Foundation for Basic Research and the Molecular and Cell Biology Program of the Russian Academy of Sciences (to Suleyman I. Allakhverdiev and Dmitry A. Los).
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