Control Of Cellular Energy Metabolism

这些研究的目的是为了更好地了解生物组织的能量代谢。为了实现这一目标，实验室专注于在蛋白质组学和翻译后修饰中使用筛选方法。在过去的一年中，我们取得了以下主要发现：1)我们之前已经表明，线粒体基质中的蛋白质磷酸化是广泛的。使用最小破坏性的蓝色天然凝胶电泳，我们已经证明了许多磷酸化线粒体氧化磷酸化复合物的激酶活性被确定存在于复合物本身。也就是说，当用蓝色原生电泳纯化不同的复合物时，复合物内的蛋白激酶活性保持不变。这意味着线粒体激酶在组成氧化磷酸化复合物的蛋白质组装中被区隔化。抗体筛选表明，这些复合物中不存在典型的胞质蛋白激酶（PKA， PKC等），这表明这些复合物本身具有独特的蛋白激酶活性。进一步的研究表明，这些蛋白磷酸化是酸敏感的，这表明它们可能代表了早期细菌蛋白磷酸化信号通路，涉及天冬氨酸和组氨酸的自磷酸化。2)一种假说认为，代谢活性波动较大的组织（如心脏和肌肉）通过翻译后修饰保留线粒体电子传递活性，而活性更恒定的组织（如肝脏）的大部分酶活性都是活跃和可用的。我们还提出，这种关系适用于不同大小的动物，其中由于基础活动的相对差异，心脏具有非常高（人，大型动物）或低（小鼠，大鼠，小动物）的动态范围。我们已经证明，线粒体复合体V和IV的活性确实遵循这一概念，在猪的心脏和骨骼肌中受到抑制，而在猪肝中完全活跃。相反，持续活跃的小鼠心脏和肝脏具有基本相同的酶活性。一种中间动物，兔子，显示出介于猪和老鼠之间的中间值。这些研究表明，在静止条件下，氧化磷酸化酶存在固有的翻译后节流，可能会阻止势能和相关活性氧的积累。

The purpose of these studies is to establish a better understanding of the energy metabolism of biological tissues. Towards this goal, the laboratory concentrates on the use of screening approaches in proteomics and post-translational modifications. The following major findings were made over the last year: 1) We have previously shown that protein phosphorylation in the mitochondria matrix is extensive. Using minimally disruptive blue native gel electrophoresis we have demonstrated that much of the kinase activity phosphorylating mitochondria oxidative phosphorylation complexes was identified to exist within the Complex itself. That is, when the different complexes were purified by blue native electrophoresis, the protein kinase activity within the complex was maintained. This implies that mitochondrial kinases are compartmentalized in the protein assemblies making up the oxidative phosphorylation complexes. Antibody screening suggested that typical cytosolic protein kinases (PKA, PKC etc) are not present in these complexes, suggesting that the complexes themselves have unique protein kinase activity. Further studies have revealed that these protein phosphorylations are acid sensitive suggesting they may represent early bacterial protein phosphorylation signaling pathways involving the autophosphorylation of aspartate and histidine. 2) A hypothesis has been developed that tissues with large swings in metabolic activity (i.e. heart and muscle) hold mitochondrial electron transport activity in reserve via post translational modifications while more constant activity tissues (i.e. liver) have most of their enzymatic activity active and available. We also propose that this relationship holds in animals of different sizes where the heart has very high (man, large animals) or low (mouse, rat, small animals) dynamic range due to their relative differences in basal activity. We have demonstrated that the activity of mitochondria Complex V and IV indeed follow this notion, being suppressed in heart and skeletal muscle of pigs while fully active in the porcine liver. In contrast, the constantly active mouse heart and liver have essentially identical enzyme activities. An intermediate animal, the rabbit, showed intermediate values between the pig and mouse. These studies suggest that an inherent post-translational throttle on oxidative phosphorylation enzymes is present likely preventing the buildup of potential energy and associated reactive oxygen species under resting conditions.