Biology subjects

Bousquet-Antonelli, C.

Publications and source records attributed to Bousquet-Antonelli, C..

3 recordsLinked to original sources

bioRxiv2024

ECT2 peptide sequences outside the YTH domain regulate its m6A-RNA binding

The m6A epitranscriptomic mark is the most abundant and widespread internal RNA chemical modification, which through the control of RNA acts as an important actor of eukaryote reproduction, growth, morphogenesis and stress response. The main m6A readers constitute a super family of proteins with hundreds of members that share a so-called YTH RNA binding domain. The majority of YTH proteins carry no obvious additional domain except for an Intrinsically Disordered Region (IDR). In Arabidopsis thaliana IDRs are important for the functional specialization among the different YTH proteins, known as Evolutionarily Conserved C-Terminal region, ECT 1 to 12. Here by studying the ECT2 protein and using an in vitro biochemical characterization, we show that full length ECT2 and its YTH domain alone have a distinct ability to bind m6A, conversely to previously characterized YTH readers. We identify peptide regions outside of ECT2 YTH domain, in the N-terminal IDR, that regulate its binding to m6A-methylated RNA. Furthermore, we show that the selectivity of ECT2 binding for m6A is enhanced by a high uridine content within its neighboring sequence, where ECT2 N-terminal IDR is believed to contact the target RNA in vivo. Finally, we also identify small structural elements, located next to ECT2 YTH domain and conserved in a large set of YTH proteins, that enhance its binding to m6A-methylated RNA. We propose from these findings that some of these regulatory regions are not limited to ECT2 or YTH readers of the flowering plants but may be widespread among the eukaryotic YTH readers.

biochemistry↗

bioRxiv2024

Genome-wide analysis of mRNA decay in Arabidopsis shoot and root reveals the importance of co-translational mRNA decay in the general mRNA turnover

Until recently, the general 5-3 mRNA decay was placed in the cytosol after the mRNA was released from ribosomes. However, the discovery of an additional 5 to 3 pathway, the Co-Translational mRNA Decay (CTRD), changed this paradigm. Up to date, defining the real contribution of CTRD in the general mRNA turnover has been hardly possible as the enzyme involved in this pathway is also involved in cytosolic decay. Here we overcame this obstacle and created an Arabidopsis line specifically impaired for CTRD called XRN4{Delta}CTRD. Through a genome-wide analysis of mRNA decay rate in shoot and root, we tested the importance of CTRD in mRNA turnover. First, we observed that mRNAs tend to be more stable in root than in shoot. Next, using XRN4{Delta}CTRD line, we demonstrated that CTRD is a major determinant in mRNA turnover. In shoot, the absence of CTRD leads to the stabilization of thousands of transcripts while in root its absence is highly compensated resulting in faster decay rates. We demonstrated that this faster decay rate is partially due to the XRN4-dependent cytosolic decay. Finally, we correlated this organ-specific effect with XRN4{Delta}CTRD line phenotypes revealing a crucial role of CTRD in mRNA homeostasis and proper organ development.

plant biology↗

bioRxiv2020

LARP6C regulates selective mRNA translation to promote pollen tube guidance in Arabidopsis thaliana.

In angiosperms, non-motile sperm cells are delivered to the ovules for fertilization via a guided growth of the pollen tube. RNA binding proteins are key regulators that control mRNA fate post-transcriptionally and thus essential for normal cell function. But very little is known on the mechanistic bases of mRNA regulations and trans-acting factors governing male-female signalling. Here we demonstrate that the evolutionarily conserved RNA binding protein LARP6C is necessary for pollen tube guidance and fertilization. larp6c loss-of-function mutants exhibit male induced fertility defects as mutant pollen tubes frequently are unable to find ovules for fertilization. In mature pollen, LARP6C localises with a pollen specific poly(A) binding protein to cytoplasmic foci likely containing mRNPs. With RNA immunoprecipitation and sequencing, we demonstrate that LARP6C is associated in vivo with mRNAs required for pollen tube guidance or polarized cell growth. We further demonstrate using in vitro and in planta transient assays that LARP6C binds 5-UTR box motifs to orchestrate the balance between translation, decay and storage of its mRNA targets. We propose a model where LARP6C maintains its mRNA target in translationally silent state likely to promote localized translation and guided pollen tube growth upon paracrine signalling.

plant biology↗