Mutation of the PEBP-like domain of the mitoribosomal MrpL35/mL38 protein results in production of nascent chains with impaired capacity to assemble into OXPHOS complexes
Mutation of the PEBP-like domain of the mitoribosomal MrpL35/mL38 protein results in production of nascent chains with impaired capacity to assemble into OXPHOS complexes
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DOI：
10.1091/mbc.e23-04-0132
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发表时间：
2023-12-01
影响因子：
3.3
通讯作者：
Stuart，Rosemary A.
中科院分区：
文献类型：
--
作者：
Box，Jodie M.;Anderson，Jessica M.;Stuart，Rosemary A.
位于有丝分裂体中央突起区域的有丝分裂特异的mL38蛋白与磷脂酰乙醇胺结合蛋白(PEBP)同源，是一个与阴离子底物/配体结合的蛋白质家族，参与细胞信号和分化途径。在这项研究中，我们对酵母有丝分裂蛋白Mr pL35/mL38进行了突变分析，并证明了PEBP不变配体结合残基Asp(D)232和Arg(R)288的突变影响了Mr pL35/mL38‘S支持基于OXPHOS的细胞生长的能力。此外，我们的数据表明这些残基存在于一个具有重要功能的带电微环境中，其中还包括Mr pL35/mL38蛋白的Asp(D)167和邻近的Mr p7/bL27m蛋白的Arg(R)127。我们报告说，这些带电残基的每个突变都导致了OXPHOS复合体水平的显著降低，这并不是由于相应的线粒体翻译过程的抑制。相反，我们的发现表明，在这些突变体中，线粒体蛋白质翻译过程与确保新合成蛋白质组装成OXPHOS酶的能力和/或可用性所需的事件之间存在脱节。根据我们的发现，我们推测mrpL35/mL38的peBP同源结构域与其合作伙伴mrp7/bL27m一起形成了有丝分裂体的关键调控区。
Located in the central protuberance region of the mitoribosome and mitospecific mL38 proteins display homology to PEBP (Phosphatidylethanolamine Binding Protein) proteins, a diverse family of proteins reported to bind anionic substrates/ligands and implicated in cellular signaling and differentiation pathways. In this study, we have performed a mutational analysis of the yeast mitoribosomal protein MrpL35/mL38 and demonstrate that mutation of the PEBP-invariant ligand binding residues Asp(D)232 and Arg(R)288 impacted MrpL35/mL38’s ability to support OXPHOS-based growth of the cell. Furthermore, our data indicate these residues exist in a functionally important charged microenvironment, which also includes Asp(D)167 of MrpL35/mL38 and Arg(R)127 of the neighboring Mrp7/bL27m protein. We report that mutation of each of these charged residues resulted in a strong reduction in OXPHOS complex levels that was not attributed to a corresponding inhibition of the mitochondrial translation process. Rather, our findings indicate that a disconnect exists in these mutants between the processes of mitochondrial protein translation and the events required to ensure the competency and/or availability of the newly synthesized proteins to assemble into OXPHOS enzymes. Based on our findings, we postulate that the PEBP-homology domain of MrpL35/mL38, together with its partner Mrp7/bL27m, form a key regulatory region of the mitoribosome.