Molecular Mechanism of the Specificity of Protein Import into Chloroplasts and Mitochondria in Plant Cells
作者机构：Division of Integrative Biosciences and Biotechnology Pohang University of Science and Technology Pohang 37673 Korea Department of Life Sciences Pohang University of Science and Technology Pohang 37673 Korea Istituto di Biologia e Biotecnologia Agraria Consiglio Nazionale Delle Ricerche Milano Italy
出 版 物：《Molecular Plant》 (分子植物（英文版）)
年 卷 期：2019年第12卷第7期
页 面：951-966页
核心收录：
学科分类：0710[理学-生物学] 07[理学] 0901[农学-作物学] 0902[农学-园艺学]
基 金：supported by the Cooperative Research Program for Agriculture Science and Technology Development Rural Development Administration, Republic of Korea the National Research Foundation of Korea (NRF) grant funded by the Korea Government, Ministry of Science and ICT supported by from the National Research Foundation, the Ministry of Science and ICT, Korea
主 题：transit peptide presequence protein import into chloroplasts and mitochondria N-terminal specificity domain C-terminal common translocation domain import specificity determination
摘 要：Plants possess both types of endosymbiotic organelles, chloroplasts and mitochondria. Transit peptides and presequences function as signal sequences for specific import into chloroplasts and mitochondria, respectively. However, how these highly similar signal sequences confer the protein import specificity remains elusive. Here, we show that mitochondrial- or chloroplast-specific import involves two distinct steps, specificity determination and translocation across envelopes, which are mediated by the N-terminal regions and functionally interchangeable C-terminal regions, respectively, of transit peptides and presequences. A domain harboring multiple-arginine and hydrophobic sequence motifs in the N-terminal regions of presequences was identified as the mitochondrial specificity factor. The presence of this domain and the absence of arginine residues in the N-terminal regions of otherwise common targeting signals confers specificity of protein import into mitochondria and chloroplasts, respectively. AtToc159, a chloroplast import receptor, also contributes to determining chloroplast import specificity. We propose that common ancestral sequences were functionalized into mitochondrial- and chloroplast-specific signal sequences by the presence and absence, respectively, of multiple-arginine and hydrophobic sequence motifs in the N-terminal region.
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