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The Arabidopsis Protein CONSERVED ONLY IN THE GREEN LINEAGE20 is Required for Plastid 50S Ribosome Biogenesis

ABSTRACT: Biogenesis of plastid ribosomes is facilitated by auxiliary factors which process and modify ribosomal RNAs (rRNA) or are involved in ribosome assembly. In comparison to their bacterial and mitochondrial counterparts, the biogenesis of plastid ribosomes is less well understood and few auxiliary factors have been described so far. In this study, we report the functional characterization of CGL20 (CONSERVED ONLY IN THE GREEN LINEAGE20) in Arabidopsis thaliana (AtCGL20) a small, proline-rich protein which is targeted to mitochondria and chloroplasts. In Arabidopsis, CGL20 is encoded by segmentally duplicated genes of high similarity (AtCGL20A and AtCGL20B), and inactivation of both in the atcgl20ab mutant leads to a visible virescent phenotype, and growth arrest at low temperature. The chloroplast proteome, thylakoid complex abundance and pigment composition are significantly affected in atcgl20ab mutants, resulting in a combined proton gradient regulation (pgr) and chlororespiratory reduction (crr) phenotype. Loss of AtCGL20 alters plastid rRNA ratios, perturbs the formation of a hidden break in 23S rRNA and causes abnormal accumulation of 50S ribosomal subunits in the high-molecular-mass fraction of chloroplast stromal extracts. Moreover, AtCGL20A-eGFP fusion proteins comigrate with 50S ribosomal subunits in sucrose density gradients, even after RNase treatment of stromal extracts. Therefore, we propose that AtCGL20 participates in late stages of the biogenesis of 50S ribosomal subunits in plastids – a role which presumably evolved in the green lineage as a consequence of structural divergence of plastid ribosomes.

OTHER RELATED OMICS DATASETS IN: PXD014514

ORGANISM(S): Arabidopsis thaliana

PROVIDER: GSE134415 | GEO | 2020/03/16

REPOSITORIES: GEO

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The Arabidopsis Protein CONSERVED ONLY IN THE GREEN LINEAGE20 is Required for Plastid 50S Ribosome Biogenesis

Project description:Biogenesis of plastid ribosomes is assisted by auxiliary factors which process and modify ribosomal RNAs (rRNA) or are involved in ribosome assembly. In comparison to bacterial and mitochondrial ribosomes, plastid ribosome biogenesis is less well understood and only few auxiliary factors have been described, so far. In this study, we report the functional characterization of CGL20 (CONSERVED ONLY IN THE GREEN LINEAGE20) in Arabidopsis thaliana (AtCGL20), a small proline-rich protein targeted to mitochondria and chloroplasts. Its absence is accompanied with a general reduction in chloroplast protein content that leads to a virescent growth phenotype.

2020-02-25 | PXD014514 | Pride

Separation and Paired Proteome Profiling of Plant Chloroplast and Cytoplasmic Ribosomes

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Ribosome protein composition in wt and 23S+5S rRNA ribosomes

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The RNA-binding protein Hfq is important for ribosome biogenesis and affects translation fidelity

Project description:Ribosome biogenesis is a complex and intricate process involving multiple factors. A plethora of auxiliary proteins assist the correct assembly of rRNA and ribosomal proteins into mature ribosomes. Defects in this process cause dysfunctional ribosomes which may alter protein synthesis and impair cell fitness. Despite its importance, yet we are lacking mechanistic details of ribosome biogenesis. Here we show that the widely-conserved RNA chaperone Hfq, which is an important post-transcriptional regulator in sRNA-mRNA basepairing in Escherichia coli, plays a critical role in rRNA processing and consequently ribosome assembly. Hfq binds the 17S rRNA precursor and facilitates its correct processing and folding to mature 16S rRNA. Strikingly, Hfq depletion decreases the pool of mature 70S ribosomes. Mutations in residues located in the distal face of Hfq render reduced ribosome levels in contrast to mutations in the proximal and rim surfaces which govern interactions with the sRNAs. Our results indicate that the described Hfq-dependent regulation of ribosomes is independent of its function as sRNA-regulator. Furthermore, we observed that inactivation of Hfq compromises translation efficiency and fidelity, both features of aberrantly assembled ribosomes. Our work expands the functions of Hfq beyond its function in small RNA-mediated regulation and unveil a novel role of Hfq as crucial auxiliary factor in ribosome biogenesis and translation.

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The Arabidopsis NOT4A E3 ligase promotes PGR3 expression and regulates chloroplast translation

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