TY - JOUR

T1 - AtRsgA from Arabidopsis thaliana is important for maturation of the small subunit of the chloroplast ribosome

AU - Janowski, Marcin

AU - Zoschke, Reimo

AU - Scharff, Lars

AU - Martinez Jaime, Silvia

AU - Ferrari, Camilla

AU - Proost, Sebastian

AU - Ng Wei Xiong, Jonathan

AU - Omranian, Nooshin

AU - Musialak-Lange, Magdalena

AU - Nikoloski, Zoran

AU - Graf, Alexander

AU - Schöttler, Mark A.

AU - Sampathkumar, Arun

AU - Vaid, Neha

AU - Mutwil, Marek

PY - 2018

Y1 - 2018

N2 - Plastid ribosomes are very similar in structure and function to ribosomes of their bacterial ancestors. Since ribosome biogenesis is not thermodynamically favourable at biological conditions, it requires activity of many assembly factors. Here, we have characterized a homolog of bacterial rsgA in Arabidopsis thaliana and show that it can complement the bacterial homolog. Functional characterization of a strong mutant in Arabidopsis revealed that the protein is essential for plant viability, while a weak mutant produced dwarf, chlorotic plants that incorporated immature pre-16S ribosomal RNA into translating ribosomes. Physiological analysis of the mutant plants revealed smaller, but more numerous chloroplasts in the mesophyll cells, reduction of chlorophyll a and b, depletion of proplastids from the rib meristem and decreased photosynthetic electron transport rate and efficiency. Comparative RNA-sequencing and proteomic analysis of the weak mutant and wild-type plants revealed that various biotic stress-related, transcriptional regulation and post-transcriptional modification pathways were repressed in the mutant. Intriguingly, while nuclear- and chloroplast-encoded photosynthesis-related proteins were less abundant in the mutant, the corresponding transcripts were increased, suggesting an elaborate compensatory mechanism, potentially via differentially active retrograde signalling pathways. To conclude, this study reveals a chloroplast ribosome assembly factor and outlines the transcriptomic and proteomic responses of the compensatory mechanism activated during decreased chloroplast function.

AB - Plastid ribosomes are very similar in structure and function to ribosomes of their bacterial ancestors. Since ribosome biogenesis is not thermodynamically favourable at biological conditions, it requires activity of many assembly factors. Here, we have characterized a homolog of bacterial rsgA in Arabidopsis thaliana and show that it can complement the bacterial homolog. Functional characterization of a strong mutant in Arabidopsis revealed that the protein is essential for plant viability, while a weak mutant produced dwarf, chlorotic plants that incorporated immature pre-16S ribosomal RNA into translating ribosomes. Physiological analysis of the mutant plants revealed smaller, but more numerous chloroplasts in the mesophyll cells, reduction of chlorophyll a and b, depletion of proplastids from the rib meristem and decreased photosynthetic electron transport rate and efficiency. Comparative RNA-sequencing and proteomic analysis of the weak mutant and wild-type plants revealed that various biotic stress-related, transcriptional regulation and post-transcriptional modification pathways were repressed in the mutant. Intriguingly, while nuclear- and chloroplast-encoded photosynthesis-related proteins were less abundant in the mutant, the corresponding transcripts were increased, suggesting an elaborate compensatory mechanism, potentially via differentially active retrograde signalling pathways. To conclude, this study reveals a chloroplast ribosome assembly factor and outlines the transcriptomic and proteomic responses of the compensatory mechanism activated during decreased chloroplast function.

KW - 30s subunit

KW - arabidopsis thaliana

KW - assembly factor

KW - chloroplast ribosome

KW - corresponding authors

KW - ribosome assembly

KW - rsga

U2 - 10.1111/tpj.14040

DO - 10.1111/tpj.14040

M3 - Journal article

C2 - 30044525

VL - 96

SP - 404

EP - 420

JO - Plant Journal

JF - Plant Journal

SN - 0960-7412

IS - 2

ER -