Around 100 proteins are produced inside the chloroplast but the vast majority must be imported. These proteins are synthesized in the cytosol as preproteins with cleavable targeting sequences. Several plastid types ot...Around 100 proteins are produced inside the chloroplast but the vast majority must be imported. These proteins are synthesized in the cytosol as preproteins with cleavable targeting sequences. Several plastid types other than chloroplasts exist. During plant development, one plastid type may be converted to another, a process referred to as plastid transition (Jarvis and Lopez-Juez, 2013). During plastid transitions, proteome remodeling occurs, and one set of imported proteins is replaced by another that is functionally adapted (Kleffmann et al., 2007). Moreover, plastid proteomes are known to be regulated in an environmentdependent fashion, and chloroplasts may respond to changing light conditions by regulating the composition and abundance of photosynthetic complexes.展开更多
Successful import of hundreds of nucleus-encoded proteins is essential for chloroplast biogenesis. The import of cytosolic precursor proteins relies on the Toc- （translocon at the outer chloroplast membrane） and Ti...Successful import of hundreds of nucleus-encoded proteins is essential for chloroplast biogenesis. The import of cytosolic precursor proteins relies on the Toc- （translocon at the outer chloroplast membrane） and Tic- （translocon at the inner chloroplast membrane） complexes. In Arabidopsis thaliana, precursor recognition is mainly mediated by outer membrane receptors belonging to two gene families： Toc34/33 and Toc159/132/120/90. The role in import and precursor selectivity of these receptors has been intensively studied, but the function of Toc90 still remains unclear. Here, we report the ability of Toc90 to support the import of Toc159 client proteins. We show that the overexpression of Toc90 partially complements the albino knockout of Toc159 and restores photoautotrophic growth. Several lines of evidence including proteome profiling demonstrate the import and accumulation of proteins essential for chloroplast biogenesis and functionality.展开更多
基金the Swiss National Science Foundation (31003A_156998 and 31003A_176191).
文摘Around 100 proteins are produced inside the chloroplast but the vast majority must be imported. These proteins are synthesized in the cytosol as preproteins with cleavable targeting sequences. Several plastid types other than chloroplasts exist. During plant development, one plastid type may be converted to another, a process referred to as plastid transition (Jarvis and Lopez-Juez, 2013). During plastid transitions, proteome remodeling occurs, and one set of imported proteins is replaced by another that is functionally adapted (Kleffmann et al., 2007). Moreover, plastid proteomes are known to be regulated in an environmentdependent fashion, and chloroplasts may respond to changing light conditions by regulating the composition and abundance of photosynthetic complexes.
文摘Successful import of hundreds of nucleus-encoded proteins is essential for chloroplast biogenesis. The import of cytosolic precursor proteins relies on the Toc- （translocon at the outer chloroplast membrane） and Tic- （translocon at the inner chloroplast membrane） complexes. In Arabidopsis thaliana, precursor recognition is mainly mediated by outer membrane receptors belonging to two gene families： Toc34/33 and Toc159/132/120/90. The role in import and precursor selectivity of these receptors has been intensively studied, but the function of Toc90 still remains unclear. Here, we report the ability of Toc90 to support the import of Toc159 client proteins. We show that the overexpression of Toc90 partially complements the albino knockout of Toc159 and restores photoautotrophic growth. Several lines of evidence including proteome profiling demonstrate the import and accumulation of proteins essential for chloroplast biogenesis and functionality.
