Two fatty acid Δ9-desaturase genes, ole1 and ole2, from Mortierella alpina complement the yeast ole1 mutation

Abstract

cerevisiae. This indicated that the M. alpina ∆9-desaturase had a substrate preference for stearic acid (18 :0) rather than palmitic acid (16 :0). Genomic clone ∆9-2 (ole2) also encoded a protein of 445 aa which had 86 % identity to the ∆9-1 and LM9 proteins and whose ORF also complemented the yeast ole1 mutation. The transcript from this gene could only be detected in one of the six M. alpina strains tested, suggesting that its expression may be strainspecific or induced under certain physiological conditions.

A third fatty acid Δ9-desaturase from Mortierella alpina with a different substrate specificity to ole1p and ole2p The EMBL accession number for the sequence reported in this paper is AJ278339.

“…S. cerevisiae strain L8e1 (MATa elo3∆ ::kanMX4 ole1∆ ::LEU2 leu2-3 leu2-112 ura3-52 his4) was constructed from L8-14C by PCR-mediated kanMX4 gene deletion of ELO3 as described below. M. alpina and S. cerevisiae strains were cultured as described previously (Wongwathanarat et al, 1999). M. alpina growth medium S2lowN was a modified version of S2GYE (MacKenzie et al, 2000) containing 0n01 % (w\v) yeast extract (Oxoid) and 0n01 % (w\v) NH % SO % .…”

“…M. alpina growth medium S2lowN was a modified version of S2GYE (MacKenzie et al, 2000) containing 0n01 % (w\v) yeast extract (Oxoid) and 0n01 % (w\v) NH % SO % . In yeast feeding experiments, unsaturated fatty acids were added at a final concentration of 0n5 mM to medium containing 1 % (w\v) tergitol NP-40 (Sigma) (Wongwathanarat et al, 1999), whereas saturated fatty acids were first dissolved in 90 % (v\v) ethanol at a concentration of 1 mM and added to medium lacking tergitol to give a final concentration of 0n04 mM. In the latter, control cultures were supplemented with 3n6% (v\v) ethanol.…”

“…The substrate for the initial ∆9-desaturation of 18 : 0 to oleic acid (18 : 1) is stearoyl-CoA, but some of the subsequent desaturation steps, including ∆12-and ∆6-desaturation, occur using the fatty acyl chains of phospholipid molecules (Jackson et al, 1998). In the oil-producing fungus Mortierella alpina most of the genes encoding the fatty acid desaturases and elongases of the LCPUFA D. A. MacKenzie and others biosynthetic pathways have been isolated and characterized (Michaelson et al, 1998 ;Huang et al, 1999 ;Sakuradani et al, 1999 ;Wongwathanarat et al, 1999 ;Parker-Barnes et al, 2000). Interestingly, two fatty acid ∆9-desaturase genes were isolated from this fungus (Wongwathanarat et al, 1999) and these have been shown to be expressed differentially in response to growth temperature and nutrient levels (A. T. Carter, unpublished results).…”

“…In the oil-producing fungus Mortierella alpina most of the genes encoding the fatty acid desaturases and elongases of the LCPUFA D. A. MacKenzie and others biosynthetic pathways have been isolated and characterized (Michaelson et al, 1998 ;Huang et al, 1999 ;Sakuradani et al, 1999 ;Wongwathanarat et al, 1999 ;Parker-Barnes et al, 2000). Interestingly, two fatty acid ∆9-desaturase genes were isolated from this fungus (Wongwathanarat et al, 1999) and these have been shown to be expressed differentially in response to growth temperature and nutrient levels (A. T. Carter, unpublished results). Multiple fatty acid ∆9-desaturases, encoded by distinct genes, have been found in a number of other organisms, including rat (Thiede et al, 1986 ; EMBL accession no.…”

Characterization of membrane-bound fatty acid desaturases

“…The enzyme was probably the most important for maintenance of proper membrane fluidity of living organismsm during the evolution. Wongwathanarat (1999) reported that the yeast Δ9-desaturase activity, compared with other fatty acid desaturases, was mostly involved to changing the membranes fluidity during temperature shift. Hsieh and Kou (2005) support this hypothesis with experiment with two fishes Ctenopharyngodon idella and Chanos chanos.…”