Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Campinas, SP, 13083-970, Brazil.
Membrane Protein Laboratory, Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, England.
Sci Rep. 2018 Feb 22;8(1):3510. doi: 10.1038/s41598-018-21740-z.
The active transport of glycolytic pyruvate across the inner mitochondrial membrane is thought to involve two mitochondrial pyruvate carrier subunits, MPC1 and MPC2, assembled as a 150 kDa heterotypic oligomer. Here, the recombinant production of human MPC through a co-expression strategy is first described; however, substantial complex formation was not observed, and predominantly individual subunits were purified. In contrast to MPC1, which co-purifies with a host chaperone, we demonstrated that MPC2 homo-oligomers promote efficient pyruvate transport into proteoliposomes. The derived functional requirements and kinetic features of MPC2 resemble those previously demonstrated for MPC in the literature. Distinctly, chemical inhibition of transport is observed only for a thiazolidinedione derivative. The autonomous transport role for MPC2 is validated in cells when the ectopic expression of human MPC2 in yeast lacking endogenous MPC stimulated growth and increased oxygen consumption. Multiple oligomeric species of MPC2 across mitochondrial isolates, purified protein and artificial lipid bilayers suggest functional high-order complexes. Significant changes in the secondary structure content of MPC2, as probed by synchrotron radiation circular dichroism, further supports the interaction between the protein and ligands. Our results provide the initial framework for the independent role of MPC2 in homeostasis and diseases related to dysregulated pyruvate metabolism.
人们认为糖酵解丙酮酸通过线粒体内膜的主动转运涉及两种线粒体丙酮酸载体亚基,即 MPC1 和 MPC2,它们组装成 150kDa 的异型寡聚物。在这里,首先描述了通过共表达策略产生人 MPC 的重组方法;然而,没有观察到大量的复合物形成,主要纯化了单个亚基。与与宿主伴侣共纯化的 MPC1 不同,我们证明 MPC2 同源寡聚体促进了丙酮酸向蛋白脂质体中的有效转运。MPC2 的衍生功能要求和动力学特征与文献中先前证明的 MPC 相似。明显的是,只有噻唑烷二酮衍生物观察到对转运的化学抑制。当在缺乏内源性 MPC 的酵母中异位表达人 MPC2 刺激生长并增加耗氧量时,MPC2 的自主转运作用在细胞中得到了验证。线粒体分离物、纯化蛋白和人工脂质双层中 MPC2 的多种寡聚体形式表明存在功能性高级复合物。同步辐射圆二色性探测到的 MPC2 二级结构含量的显著变化进一步支持了蛋白质与配体之间的相互作用。我们的研究结果为 MPC2 在与丙酮酸代谢失调相关的稳态和疾病中的独立作用提供了初步框架。