Molecular Analysis of Rice Mitochondrial F_0F_1-ATPase and Effect of Mineral Element Deficienct on the Enzyme

(1)以百合（Lilium longiflorum）代替水稻（Oryza sativa）作为主要试验植物。(2)从百合和水稻的线粒体中纯化出F_1-ATPase，达到同源性。两种酶均由5种亚基组成。制备了百合F_1-ATPase抗体。从百合亚线粒体颗粒（SMP）中也纯化到了f_0f_1 - atp酶；然而，百合f_0f_1 - atp酶的亚基构成仍有待解决。(3)纯化F_0F_1-ATPase后发现SMP上F_0F_1-ATPase具有组织特异性活性。花粉f_0f_1 - atp酶活性最高，鳞茎活性最低。(4)从不同组织分离的F_0F_1-ATPases中，F_0-部分的不同性质可能导致F_0-部分与f_1 -部分的交叉重构实验判断，F_0-部分具有组织特异性活性。此外，F_0F_1-ATPase的f_0部分所在的膜的脂质组成在不同的被测组织中也不同。(5)从SMP中分离纯化了f_0f_1 - atp酶抑制蛋白。该抑制剂分子量为16kd。抑制蛋白在球茎中的含量比在花粉中的含量要高。我们在本研究中发现的抑制剂将对进一步研究f_0f_1 - atp酶的分子形式至关重要。(6)我们试图利用培养的水稻细胞来评估矿物质元素对线粒体f_0f_1 - atp酶的作用。锌和锰缺乏导致SMP上f_0f_1 - atp酶活性严重降低。锌锰饥饿降低f_0f_1 - atp酶活性的机制尚不清楚。

(1) Lily plant (Lilium longiflorum) was used as a major experimental plant instead of rice (Oryza sativa).(2) F_1-ATPase was purified from mitochondria of lily and rice plants to a homogeneity. Both enzymes consisted of 5 kinds of subunits. Antibody against lily F_1-ATPase was prepared using rabbit. F_0F_1-ATPase was also purified from submitochondrial particles (SMP) of lily plants ; however, subunit constitution of the lily F_0F_1-ATPase remains to be solved.(3) We found a tissue-specific activity of F_0F_1-ATPase on SMP when purified F_0F_1-ATPase. Pollen F_0F_1-ATPase showed the highest activity among the tissues tested and bulbs the lowest one.(4) Different properties of F_0-portions in F_0F_1-ATPases isolated from different tissues may cause the tissue-specific activities, judged from the experiments of cross-reconstitution of F_0- and F_1-portions. In addition, lipid composition of the membrane where F_0-portion of F_0F_1-ATPase locates was also different among the different tissues tested.(5) We isolated and purified an F_0F_1-ATPase inhibitor protein from SMP.The molecular size of the inhibitor was 16 kd. The inhibitor protein appeared to be present in bulbs in a larger amount than in pollens. The inhibitor we found in this study will be crucial to further investigate the molecular form of F_0F_1-ATPase.(6) We have attempted to evaluate the role of mineral elements for mitochondrial F_0F_1-ATPase using cultured rice cells. Zinc- and manganese-deficiency caused a severe reduction of F_0F_1-ATPase activity on SMP.Mechanism of reduction of F_0F_1-ATPase activity by zinc and manganese starvation remains to be solved.