Goodrich-Tanrikulu M, Stafford A E, Lin J T, McKeon T A
U.S. Department of Agriculture, Agricultural Research Service, Albany, CA 94710, USA.
Appl Microbiol Biotechnol. 1996 Nov;46(4):382-7. doi: 10.1007/BF00166233.
Neurospora crassa is a potential expression system for evaluating fatty-acid-modifying genes from plants producing uncommon fatty acids. One such gene encodes the hydroxylase that converts oleate to ricinoleate, a fatty acid with important industrial uses. To develop this expression system, it is critical to evaluate the metabolism and physiological effects of the expected novel fatty acid(s). We therefore examined effects of ricinoleate on lipid biosynthesis and growth of N. crassa. Ricinoleate inhibited growth and reduced levels of phospholipids and 2-hydroxy fatty acids in glycolipids, but led to increased lipid accumulation on a mass basis. To evaluate incorporation and metabolism of ricinoleate, we followed the fate 14 microM-3mM [1-14C]ricinoleate. The fate of the [14C]ricinoleate was concentration-dependent. At higher concentrations, ricinoleate was principally incorporated into triacylglycerols. At lower concentrations, ricinoleate was principally metabolized to other compounds. Thus, N. crassa transformants expressing the hydroxylase gene can be detected if the level of hydroxylase expression allows both growth and ricinoleate accumulation.
粗糙脉孢菌是一种潜在的表达系统，可用于评估来自产生不常见脂肪酸的植物的脂肪酸修饰基因。其中一个这样的基因编码将油酸转化为蓖麻油酸的羟化酶，蓖麻油酸是一种具有重要工业用途的脂肪酸。为了开发这个表达系统，评估预期的新型脂肪酸的代谢和生理效应至关重要。因此，我们研究了蓖麻油酸对粗糙脉孢菌脂质生物合成和生长的影响。蓖麻油酸抑制生长并降低糖脂中磷脂和2-羟基脂肪酸的水平，但导致以质量计的脂质积累增加。为了评估蓖麻油酸的掺入和代谢，我们追踪了14微摩尔至3毫摩尔[1-14C]蓖麻油酸的去向。[14C]蓖麻油酸的去向是浓度依赖性的。在较高浓度下，蓖麻油酸主要掺入三酰甘油中。在较低浓度下，蓖麻油酸主要代谢为其他化合物。因此，如果羟化酶表达水平既能支持生长又能积累蓖麻油酸，那么就可以检测到表达羟化酶基因的粗糙脉孢菌转化体。
