Open AccessLow‐temperature‐induced desaturation of fatty acids and expression of desaturase genes in the cyanobacterium Synechococcus sp. PCC 7002
Author(s) -
Sakamoto Toshio,
Higashi Shoichi,
Wada Hajime,
Murata Norio,
Bryant Donald A.
Publication year - 1997
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1997.tb10445.x
Subject(s) - gene , synechococcus , cyanobacteria , biochemistry , gene expression , fatty acid desaturase , stearoyl coa desaturase , chemistry , fatty acid , biology , bacteria , genetics , polyunsaturated fatty acid
Changes in response to temperature of lipid classes, fatty acid composition and mRNA levels for acyl‐lipid desaturase genes were studied in the marine unicellular cyanobacterium, Synechococcus sp. PCC 7002. The degree of unsaturation of C 18 fatty acids increased in cells grown at lower temperature for all lipid classes, and ω3 desaturation occurred specifically in cells grown at low temperature. While the level of 18:1(9) fatty acids declined, desaturation at the ω3 position of C 18 fatty acids increased gradually during a 12‐h period after a temperature shift‐down to 22°C. However, the mRNA levels of the desA (Δ12 desaturase), desB (ω3 desaturase) and desC (Δ9 desaturase) genes increased within 15 min after a temperature shift‐down to 22°C; the desaturase gene mRNA levels also rapidly declined within 15 min after a temperature shift‐up to 38°C. Therefore, the elevation of mRNA levels for the desaturase genes is not the rate‐limiting event for the increased desaturation of membrane lipids after a temperature shift‐down. The rapid, low‐temperature‐induced changes in mRNA levels occurred even when cells were grown under light‐limiting conditions for which the growth rates at 22°C and 38°C were identical. These studies indicate that the ambient growth temperature, and not some other growth rate‐related process, regulates the expression of acyl lipid desaturation in this cyanobacterium.