Temperature adaptation in Dictyostelium: role of Delta5 fatty acid desaturase.
Temperature adaptation in Dictyostelium: role of Delta5 fatty acid desaturase.
复制标题
盘基网柄菌的温度适应：Delta5 脂肪酸去饱和酶的作用。
作者：
Tamao Saito;A. Kato;H. Ochiai;N. Morita
膜流动性对于适当的膜功能是至关重要的，并且部分地由膜脂质中存在的不饱和脂肪酸的比例调节。这些脂质的比例又随温度而变化，可能有助于变温生物的温度适应。在这项研究中提出的基本问题是脂肪酸的不饱和度是否有助于在Dictyosteroid适应温度胁迫的能力。首先，分析脂肪酸组成，并观察到二烯酸的相对比例随温度而变化。为了研究二烯脂肪酸在温度适应中的作用，在两种已知的Delta 5脂肪酸去饱和酶（FadA和FadB）中产生无效突变体，所述Delta 5脂肪酸去饱和酶负责二烯脂肪酸的产生。fadB无效突变体在脂肪酸组成或表型方面没有显着改变。然而，fadA的破坏导致二烯脂肪酸含量从51.2%大幅下降至4.1%，并且单烯脂肪酸可能补偿性增加（40.9- 92.4%）。与野生型细胞在生长期的温度适应没有差异。然而，令人惊讶的是，突变体细胞在高温下比野生型更有效地发育。这些结果表明，脂肪酸组成的Dictyosteoprotein随温度的变化，并建议，调节二烯脂肪酸的合成参与Dictyosteoprotein在高温下的发展，但不是在生长阶段。
Membrane fluidity is critical for proper membrane function and is regulated in part by the proportion of unsaturated fatty acids present in membrane lipids. The proportion of these lipids in turn varies with temperature and may contribute to temperature adaptation in poikilothermic organisms. The fundamental question posed in this study was whether the unsaturation of fatty acids contributes to the ability to adapt to temperature stress in Dictyostelium. First, fatty acid composition was analysed and it was observed that the relative proportions of dienoic acids changed with temperature. To investigate the role of dienoic fatty acids in temperature adaptation, null mutants were created in the two known Delta5 fatty acid desaturases (FadA and FadB) that are responsible for the production of dienoic fatty acids. The fadB null mutant showed no significant alteration in fatty acid composition or in phenotype. However, the disruption of fadA resulted in a large drop in dienoic fatty acid content from 51.2 to 4.1 % and a possibly compensatory increase in monoenoic fatty acids (40.9-92.4 %). No difference was detected in temperature adaptation with that of wild-type cells during the growth phase. However, surprisingly, mutant cells developed more efficiently than the wild-type at elevated temperatures. These results show that the fatty acid composition of Dictyostelium changes with temperature and suggest that the regulation of dienoic fatty acid synthesis is involved in the development of Dictyostelium at elevated temperatures, but not during the growth phase.