DesA gene

Vigh L., Los D. A., Hovath I. and Murata N. (1993) The primary signal in the biological perception of temperature Pd-catalyzed hydrogenation of membrane lipids stimulated the expression of the desA gene in Synechocystis PCC6803. Proc. Natl. Acad. Sci. USA 90, 9090-9094. 

Overexpression of the desA gene in E. coll and site-directed mutagenesis. 

We recently compared changes in the levels of itiRNAs for all four desaturases from Synechocystis sp. PCC 6803 upon a decrease of ambient temperature, and we found that the level of mRNA transcribed from the desC gene stayed constant regardless of the temperature. The levels of mRNAs transcribed from the desB and the desD genes, which encode the co3 and A6 desaturases, respectively, responded to a decrease in temperature most rapidly. The desA gene for the A12 desaturase responded rather slowly to a change in temperature. 

Wada H, Macherel MH, Murata N. The desA gene of the cyanobacterium Synechocystis sp. strain PCC6803 is the structural gene for A12 desaturase. J Bacteriol 1993 175 6056-6058. 

Figure 1. The change in level of mRNA of the desA gene 30 min following either hydrogenation for various time intervals under isothermal conditions at 36 °C or temperature shift to 22 °C. For details see [2,5].

A shift in temperature from 38 to 22 °C leads to desaturation of fatty acids in Anabaena variabilis [110], resulting in control of the fluidity of the plasma membrane. Mutants have been isolated in Synechocystis PCC 6803 that were defective in desaturation of fatty acids, and the growth rate of one of these mutants was much lower than that of the wild-type at 22 °C [112]. It turned out that the mutant strain had a mutation in the gene desA, and when the wild-type allele was introduced into the chilling-sensitive cyanobacterium Anacystis nidulans, it resulted in increasing the tolerance of that strain to low temperature [113]. These experiments nicely demonstrate the existence of a mechanism of adaptation to low temperature in a chilling-tolerant cyanobacterium. 

In Synechococcus sp. strain PCC 7002, the temperature-regulated mRNA accumulation of the three desaturase genes, desA (A12 desaturase), desB (co3... 

The effects of the unsaturation of fatty acids on membrane fluidity has also been extensively studied in two strains of cyanobacteria, Synechocystis sp. PCC 6803 and Synechococcus sp. PCC 7942 (Los and Murata, 2004). The genes for four specific acyl-lipid desaturases, designated desA, desB, desC and desD, have been cloned from Synechocystis. These desaturases introduce double bonds at the A12 (Sakamoto and Bryant, 1997), ( 3 (Sakamoto et al., 1994a), A9 (Sakamoto and Bryant, 1997 Sakamoto et al., 1994b), and A6 (Reddy et al.,... 

Los, D., Horvath, L, Vigh, L. and Murata, N. The temperature-dependent expression of the desaturase gene desA in Synechocystis PCC6803. FEBS Lett, 318 (1993) 57-60. 

The fabA gene encodes the dehydratase or isomerase specifically required for the production of unsaturated fatty acids in gram-negative bacteria. Gram-positive bacteria do not contain an identifiable fabA homolog in their genome, but do possess unsaturated fatty acids. In Bacillus, it has been shown that a cold shock-induced gene (desA) encodes a desaturase... 

Xue BY, Rooney AP, Kajikawa M, Okada N, Roelofs WL (2007) Novel sex pheromone desa-turases in the genomes of com borers generated through gene duplication and retroposon fusion. Proc Natl Acad Sci USA 104 4467 1472... 

Demin, A. N., Deryabin, A. N., Sinkevich, M. S., and Trunova, T. I. Introduction of gene desA. 12-acyl-lipid desaturase of cyanobacterium enhange the resistance of potapo plants to oxidative stress caused by hypothermia. Plant Physiol. (Rus), 55 710-720 (2000). 

A decrease in the ambient temperature induces desaturation of fatty acids of membrane lipids [18]. We have demonstrated that the desaturation results from the low-temperature-induced regulation of expression of genes for desaturases [19]. We have also obtained evidence that a decrease in the fluidity of plasma membranes of Synechocystis sp. PCC 6803 by catalytic hydrogenation can mimic a decrease in temperature in regulating the level of desA mRNA [20]. 

We compared the lifetimes of mRNAs for the four desaturases at 22 C and 34°C. The half-lives of mRNAs transcribed from the desA, desB and desD genes at 22 C were 20, 10, 20 minutes, respectively, whereas those at 34 C were less than one-tenth of these values [Los DA, Murata N, unpublished]. These observations suggest that the levels of the mRNAs are regulated in response to temperature by changes in the rates of degradation of the... 

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