Ranganathan G, Mukkada A J
Department of Biological Sciences, University of Cincinnati, OH 45221, USA.
Int J Parasitol. 1995 Mar;25(3):279-84. doi: 10.1016/0020-7519(94)00131-7.
Promastigotes of Leishmania major contain a ubiquinone which has a side chain made up of nine isoprene subunits (UQ9). Incorporation of radioactivity from [14C] acetate and [14C] mevalonate into ubiquinone as well as the identification of hydroxymethylglutaryl coenzyme A reductase (HMG CoA reductase), and mevalonate kinase indicate that the isoprenoid portion of the molecule is synthesized by the acetate-mevalonate pathway as in mammalian cells. Incorporation of [14C] tyrosine into ubiquinone is low, but [14C] parahydroxybenzoic acid is readily incorporated. Distribution of radioactivity from [14C] acetate indicates that about 60-80% is associated with the side chain and about 20% with the ring. Label from parahydroxybenzoic acid is, however, incorporated preferentially into the ring. L. major is capable of synthesizing the aromatic ring of ubiquinone from acetate, parahydroxybenzoate being an important intermediate. In this behaviour it resembles procaryotes. Ubiquinone biosynthetic pathway in L. major thus shares characteristics with mammalian and bacterial systems.
硕大利什曼原虫的前鞭毛体含有一种泛醌，其侧链由九个异戊二烯亚基组成（UQ9）。[14C]乙酸盐和[14C]甲羟戊酸的放射性掺入泛醌以及羟甲基戊二酰辅酶A还原酶（HMG CoA还原酶）和甲羟戊酸激酶的鉴定表明，该分子的类异戊二烯部分如在哺乳动物细胞中一样由乙酸盐-甲羟戊酸途径合成。[14C]酪氨酸掺入泛醌的量较低，但[14C]对羟基苯甲酸很容易掺入。[14C]乙酸盐的放射性分布表明，约60 - 80%与侧链相关，约20%与环相关。然而，对羟基苯甲酸的标记优先掺入环中。硕大利什曼原虫能够从乙酸盐合成泛醌的芳香环，对羟基苯甲酸盐是一个重要的中间体。在这种行为上它类似于原核生物。因此，硕大利什曼原虫的泛醌生物合成途径具有与哺乳动物和细菌系统共同的特征。
