Saccharomyces cerevisiae contains four fatty acid activation (FAA) genes: an assessment of their role in regulating protein N-myristoylation and cellular lipid metabolism.
Saccharomyces cerevisiae contains four fatty acid activation (FAA) genes: an assessment of their role in regulating protein N-myristoylation and cellular lipid metabolism.
复制标题
DOI：
10.1083/jcb.127.3.751
复制
发表时间：
1994-11
期刊：
影响因子：
--
通讯作者：
Gordon JI
中科院分区：
文献类型：
--
作者：
Johnson DR;Knoll LJ;Levin DE;Gordon JI
酿酒酵母已被用作研究蛋白质N-豆蔻酰化调节的模型。肉豆蔻酰辅酶A：N-肉豆蔻酰转移酶蛋白（Nmt 1 p），是营养生长所必需的，并使用肉豆蔻酰辅酶A作为其底物。肉豆蔻酰辅酶A由脂肪酸合成酶（Fas）复合物和细胞酰基辅酶A合成酶产生。我们最近分离出三个非连锁脂肪酸激活（FAA）基因编码长链酰基辅酶A合成酶，现在已经恢复了第四个基因互补。当Fas是活跃的，NMT 1细胞生长在含有可发酵碳源的培养基上时，营养生长不需要任何FAA基因。当Fas被特异性抑制剂（浅蓝菌素）灭活时，除非培养基中补充长链脂肪酸，否则NMT 1细胞无法存活。通过激活输入的肉豆蔻酸（C14：0）补充细胞肉豆蔻酰CoA库主要是Faa 1 p的功能，尽管Faa 4p有助于该过程。具有nmt 181 p的细胞需要更大的肉豆蔻酰CoA池，因为突变酶对该底物的亲和力降低。Faa 1 p和Faa 4p是维持nmt 1 -181菌株活力所必需的，即使Fas是活性的。Faa 2 p的过表达可以拯救nmt 1 -181细胞，这是由于C14：0的内源性库的激活。该池似乎部分源自膜磷脂，因为Plb 1 p（一种非必需的溶血磷脂酶/磷脂酶B）的过表达抑制了nmt 1 -181产生的温度敏感性生长停滞和C14：0营养缺陷型。四种已知的FAA中没有一种专门负责将进口脂肪酸靶向过氧化物酶体β-氧化途径。将过氧化物酶体组装突变pas 1 delta引入具有野生型FAA等位基因的同基因NMT 1和nmt 1 -181菌株中，发现当Fas被抑制时，过氧化物酶体有助于Nmt 1 p使用的肉豆蔻酰CoA池。当Fas有活性时，一部分细胞肉豆蔻酰CoA被靶向过氧化物酶体。缺失所有四种FAA的NMT 1菌株在30 ℃下在含有肉豆蔻酸盐、棕榈酸盐或油酸盐作为唯一碳源的培养基上仍然存活-这表明S。酿酒酵母含有至少一种将脂肪酸引导至β-氧化途径的其它FAA。
Saccharomyces cerevisiae has been used as a model for studying the regulation of protein N-myristoylation. MyristoylCoA:protein N- myristoyl-transferase (Nmt1p), is essential for vegetative growth and uses myristoylCoA as its substrate. MyristoylCoA is produced by the fatty acid synthetase (Fas) complex and by cellular acylCoA synthetases. We have recently isolated three unlinked Fatty Acid Activation (FAA) genes encoding long chain acylCoA synthetases and have now recovered a fourth by genetic complementation. When Fas is active and NMT1 cells are grown on media containing a fermentable carbon source, none of the FAA genes is required for vegetative growth. When Fas is inactivated by a specific inhibitor (cerulenin), NMT1 cells are not viable unless the media is supplemented with long chain fatty acids. Supplementation of cellular myristoylCoA pools through activation of imported myristate (C14:0) is predominantly a function of Faa1p, although Faa4p contributes to this process. Cells with nmt181p need larger pools of myristoylCoA because of the mutant enzyme's reduced affinity for this substrate. Faa1p and Faa4p are required for maintaining the viability of nmt1-181 strains even when Fas is active. Overexpression of Faa2p can rescue nmt1-181 cells due to activation of an endogenous pool of C14:0. This pool appears to be derived in part from membrane phospholipids since overexpression of Plb1p, a nonessential lysophospholipase/phospholipase B, suppresses the temperature-sensitive growth arrest and C14:0 auxotrophy produced by nmt1-181. None of the four known FAAs is exclusively responsible for targeting imported fatty acids to peroxisomal beta-oxidation pathways. Introduction of a peroxisomal assembly mutation, pas1 delta, into isogenic NMT1 and nmt1-181 strains with wild type FAA alleles revealed that when Fas is inhibited, peroxisomes contribute to myristoylCoA pools used by Nmt1p. When Fas is active, a fraction of cellular myristoylCoA is targeted to peroxisomes. A NMT1 strain with deletions of all four FAAs is still viable at 30 degrees C on media containing myristate, palmitate, or oleate as the sole carbon source--indicating that S. cerevisiae contains at least one other FAA which directs fatty acids to beta-oxidation pathways.