Mutational Analysis of the QRRQ Motif in the Yeast Hig1 Type 2 Protein Rcf1 Reveals a Regulatory Role for the Cytochrome c Oxidase Complex
Mutational Analysis of the QRRQ Motif in the Yeast Hig1 Type 2 Protein Rcf1 Reveals a Regulatory Role for the Cytochrome c Oxidase Complex
复制标题
DOI：
10.1074/jbc.m116.758045
复制
发表时间：
2017-03-31
影响因子：
4.8
通讯作者：
Stuart, Rosemary A.
中科院分区：
文献类型：
--
作者：
Garlich, Joshua;Strecker, Valentina;Stuart, Rosemary A.
酵母Rcf1蛋白是被称为缺氧诱导基因（结构域）1 （Hig1或HIGD1）家族的保守蛋白家族的成员。Rcf1与线粒体氧化磷酸化系统的组分相互作用，特别是细胞色素bc(1)（复合体III）-细胞色素c氧化酶（复合体IV）超复合体（称为III-IV）和ADP/ATP载体蛋白。Rcf1参与复合物IV的组装和活性调节；然而，Rcf1如何影响复合物IV活性的分子基础目前尚不清楚。包括Rcf1蛋白在内的Hig1 2型亚型，其部分特征在于存在一个保守基序（Q/I） X-3(R/H) XRX(3)Q，这里称为QRRQ基序。我们发现Rcf1 QRRQ基序中保守残基的突变改变了Rcf1与伴侣蛋白之间的相互作用，导致复合物IV的不稳定和酶性质的改变。我们的研究结果表明，Rcf1不作为化学计量成分，即作为配合物IV的亚基，以支持其活性。相反，我们认为Rcf1在其组装过程中与复合体IV动态相互作用，并在此过程中调节复合体IV的后期成熟步骤。我们推测Rcf1/Hig1蛋白在脂质（特别是心磷脂）结合和/或重塑复合体IV和中发挥作用。可能还有其他线粒体蛋白，如ADP/ATP载体蛋白。
The yeast Rcf1 protein is a member of the conserved family of proteins termed the hypoxia-induced gene (domain) 1 (Hig1 or HIGD1) family. Rcf1 interacts with components of the mitochondrial oxidative phosphorylation system, in particular the cytochrome bc(1) (complex III)-cytochrome c oxidase (complex IV) supercomplex (termed III-IV) and the ADP/ATP carrier proteins. Rcf1 plays a role in the assembly and modulation of the activity of complex IV; however, the molecular basis for how Rcf1 influences the activity of complex IV is currently unknown. Hig1 type 2 isoforms, which include the Rcf1 protein, are characterized in part by the presence of a conserved motif, (Q/I) X-3(R/H) XRX(3)Q, termed here the QRRQ motif. We show that mutation of conserved residues within the Rcf1 QRRQ motif alters the interactions between Rcf1 and partner proteins and results in the destabilization of complex IV and alteration of its enzymatic properties. Our findings indicate that Rcf1 does not serve as a stoichiometric component, i.e. as a subunit of complex IV, to support its activity. Rather, we propose that Rcf1 serves to dynamically interact with complex IV during its assembly process and, in doing so, regulates a late maturation step of complex IV. We speculate that the Rcf1/Hig1 proteins play a role in the incorporation and/or remodeling of lipids, in particular cardiolipin, into complex IV and. possibly, other mitochondrial proteins such as ADP/ATP carrier proteins.