The complexity of pathways for protein import into thylakoids: it's not easy being green

Cola, Alessandra Di; Klostermann, Eva; Robinson, Colin

doi:10.1042/bst20051024

Cited by 14 publications

(1 citation statement)

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“…Most of the chloroplast proteins are encoded by nuclear genes, translated in the cytosol as precursor proteins, and post-translationally imported into the chloroplast stroma 9 . From the stroma, some intermediate precursors are translocated into or across the thylakoid membrane 10 . Because the majority of the several thousands of chloroplast proteins are encoded by the nucleus, it is not surprising that numerous mutants that are disrupted in chloroplast biogenesis have mutations on nuclear-encoded genes with diverse biological functions, including biosynthesis of photosynthetic pigments, thylakoid biogenesis, lipid biosynthesis, protein import, photosystem assembly, protein maturation and degradation and plastid gene expression 11 12 13 14 15 16 17 18 .…”

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The novel protein DELAYED PALE-GREENING1 is required for early chloroplast biogenesis in Arabidopsis thaliana

Liu

Cheng

2016

Sci Rep

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Chloroplast biogenesis is one of the most important subjects in plant biology. In this study, an Arabidopsis early chloroplast biogenesis mutant with a delayed pale-greening phenotype (dpg1) was isolated from a T-DNA insertion mutant collection. Both cotyledons and true leaves of dpg1 mutants were initially albino but gradually became pale green as the plant matured. Transmission electron microscopic observations revealed that the mutant displayed a delayed proplastid-to-chloroplast transition. Sequence and transcription analyses showed that AtDPG1 encodes a putatively chloroplast-localized protein containing three predicted transmembrane helices and that its expression depends on both light and developmental status. GUS staining for AtDPG1::GUS transgenic lines showed that this gene was widely expressed throughout the plant and that higher expression levels were predominantly found in green tissues during the early stages of Arabidopsis seedling development. Furthermore, quantitative real-time RT-PCR analyses revealed that a number of chloroplast- and nuclear-encoded genes involved in chlorophyll biosynthesis, photosynthesis and chloroplast development were substantially down-regulated in the dpg1 mutant. These data indicate that AtDPG1 plays an essential role in early chloroplast biogenesis, and its absence triggers chloroplast-to-nucleus retrograde signalling, which ultimately down-regulates the expression of nuclear genes encoding chloroplast-localized proteins.

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confidence: 99%

The novel protein DELAYED PALE-GREENING1 is required for early chloroplast biogenesis in Arabidopsis thaliana

Liu

Cheng

2016

Sci Rep

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How do endosymbionts become organelles? Understanding early events in plastid evolution

et al. 2007

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What factors drove the transformation of the cyanobacterial progenitor of plastids (e.g. chloroplasts) from endosymbiont to bona fide organelle? This question lies at the heart of organelle genesis because, whereas intracellular endosymbionts are widespread in both unicellular and multicellular eukaryotes (e.g. rhizobial bacteria, Chlorella cells in ciliates, Buchnera in aphids), only two canonical eukaryotic organelles of endosymbiotic origin are recognized, the plastids of algae and plants and the mitochondrion. Emerging data on (1) the discovery of non-canonical plastid protein targeting, (2) the recent origin of a cyanobacterial-derived organelle in the filose amoeba Paulinella chromatophora, and (3) the extraordinarily reduced genomes of psyllid bacterial endosymbionts begin to blur the distinction between endosymbiont and organelle. Here we discuss the use of these terms in light of new data in order to highlight the unique aspects of plastids and mitochondria and underscore their central role in eukaryotic evolution.

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The Chloroplast Protein Import Machinery: A Review

Strittmatter

Soll

Bölter

2010

Methods in Molecular Biology

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Plastids are a heterogeneous family of organelles found ubiquitously in plants and algal cells. Most prominent are the chloroplasts, which carry out such essential processes as photosynthesis and the biosynthesis of fatty acids as well as of amino acids. As mitochondria, chloroplasts are derived from a single endosymbiotic event. They are believed to have evolved from an ancient cyanobacterium, which was engulfed by an early eukaryotic ancestor. During evolution the plastid genome has been greatly reduced and most of the genes have been transferred to the host nucleus. Consequently, more than 98% of all plastid proteins are translated on cytosolic ribosomes. They have to be posttranslationally targeted to and imported into the organelle. Targeting is assisted by cytosolic proteins which interact with proteins destined for plastids and thereby keep them in an import competent state. After reaching the target organelle, many proteins have to conquer the barrier of the chloroplast outer and inner envelope. This process is mediated by complex molecular machines in the outer (Toc complex) and inner (Tic complex) envelope of chloroplasts, respectively. Most proteins destined for the compartments inside the chloroplast contain a cleavable N-terminal transit peptide, whereas most of the outer envelope components insert into the membrane without such a targeting peptide.

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The complexity of pathways for protein import into thylakoids: it's not easy being green

Cited by 14 publications

References 40 publications

The novel protein DELAYED PALE-GREENING1 is required for early chloroplast biogenesis in Arabidopsis thaliana

The novel protein DELAYED PALE-GREENING1 is required for early chloroplast biogenesis in Arabidopsis thaliana

How do endosymbionts become organelles? Understanding early events in plastid evolution

The Chloroplast Protein Import Machinery: A Review

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