Bunney T D, van Walraven H S, de Boer A H
Department of Developmental Genetics, Vrije Universiteit, Faculty of Biology, BioCentrum Amsterdam, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands.
Proc Natl Acad Sci U S A. 2001 Mar 27;98(7):4249-54. doi: 10.1073/pnas.061437498. Epub 2001 Mar 13.
Mitochondrial and chloroplast ATP synthases are key enzymes in plant metabolism, providing cells with ATP, the universal energy currency. ATP synthases use a transmembrane electrochemical proton gradient to drive synthesis of ATP. The enzyme complexes function as miniature rotary engines, ensuring energy coupling with very high efficiency. Although our understanding of the structure and functioning of the synthase has made enormous progress in recent years, our understanding of regulatory mechanisms is still rather preliminary. Here we report a role for 14-3-3 proteins in the regulation of ATP synthases. These 14-3-3 proteins are highly conserved phosphoserine/phosphothreonine-binding proteins that regulate a wide range of enzymes in plants, animals, and yeast. Recently, the presence of 14-3-3 proteins in chloroplasts was illustrated, and we show here that plant mitochondria harbor 14-3-3s within the inner mitochondrial-membrane compartment. There, the 14-3-3 proteins were found to be associated with the ATP synthases, in a phosphorylation-dependent manner, through direct interaction with the F(1) beta-subunit. The activity of the ATP synthases in both organelles is drastically reduced by recombinant 14-3-3. The rapid reduction in chloroplast ATPase activity during dark adaptation was prevented by a phosphopeptide containing the 14-3-3 interaction motif, demonstrating a role for endogenous 14-3-3 in the down-regulation of the CF(o)F(1) activity. We conclude that regulation of the ATP synthases by 14-3-3 represents a mechanism for plant adaptation to environmental changes such as light/dark transitions, anoxia in roots, and fluctuations in nutrient supply.
线粒体和叶绿体ATP合酶是植物新陈代谢中的关键酶，为细胞提供通用能量货币ATP。ATP合酶利用跨膜电化学质子梯度驱动ATP的合成。这些酶复合物起着微型旋转发动机的作用，确保能量高效耦合。尽管近年来我们对合酶的结构和功能的理解取得了巨大进展，但对其调控机制的理解仍相当初步。在此，我们报道了14-3-3蛋白在ATP合酶调控中的作用。这些14-3-3蛋白是高度保守的磷酸丝氨酸/磷酸苏氨酸结合蛋白，在植物、动物和酵母中调节多种酶。最近，叶绿体中14-3-3蛋白的存在得到了证实，我们在此表明植物线粒体在内膜间隙中含有14-3-3蛋白。在那里，发现14-3-3蛋白通过与F(1)β亚基直接相互作用，以磷酸化依赖的方式与ATP合酶相关联。重组14-3-3可使两种细胞器中ATP合酶的活性大幅降低。含有14-3-3相互作用基序的磷酸肽可防止暗适应过程中叶绿体ATP酶活性的快速降低，这表明内源性14-3-3在CF(o)F(1)活性下调中起作用。我们得出结论，14-3-3对ATP合酶的调控代表了植物适应环境变化的一种机制，如光/暗转换、根部缺氧和营养供应波动。
