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Arabidopsis mTERF9 protein promotes chloroplast ribosomal assembly and translation by establishing ribonucleoprotein interactions in vivo

ABSTRACT: The mitochondrial transcription termination factor proteins are nuclear-encoded nucleic acid binders defined by degenerate tandem helical-repeats of ~30 amino acids. They are found in metazoans and plants where they localize in organelles. In higher plants, the mTERF family comprises ~30 members and several of these have been linked to plant development and response to abiotic stress. However, knowledge of the molecular basis underlying these physiological effects is scare. We show that the Arabidopsis mTERF9 protein, promotes the accumulation of the 16S rRNA and the formation of the 23S rRNA first hidden break in chloroplasts, and co-immunoprecipitates with the 16S rRNA. Furthermore, mTERF9 is found in large complexes containing ribosomes and polysomes in chloroplasts. The analysis of the in vivo mTERF9 protein interactome identified many ribosomal proteins whose assembly into 70S ribosomes is compromised in the null mterf9 mutant. mTERF9 additionally interacts with putative ribosome biogenesis factors and CPN60 chaperonins. Yeast protein interaction assays revealed that mTERF9 has the capacity to directly interact with these proteins. Our data demonstrate that mTERF9 integrates protein-protein and protein-RNA interactions to promote chloroplast ribosomal assembly and translation. Besides extending our knowledge of mTERF molecular functions in plants, these findings provide important insight into the chloroplast ribosome biogenesis.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Leaf

SUBMITTER: Lauriane Kuhn

LAB HEAD: Kamel Hammani

PROVIDER: PXD018987 | Pride | 2020-12-15

REPOSITORIES: Pride

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