Perrot, L. | bioRxiv Science

bioRxiv2024

NMR at operational temperature for resonance assignments of a PET degrading enzyme

PETases are enzymes that can break down the poly-ethylene terephthalate (PET) polymer in its constituent building blocks. This enzymatic recycling process offers a sustainable solution for producing new, high-quality plastics from previously used materials. NMR spectroscopy can help in understanding and ultimately improving these enzymes but is always confronted with the lengthy step of acquisition and interpretation of triple resonance spectra for the spectral assignment. Here, we explore whether this step can be made more efficient by recording the spectra directly at high temperature, which simultaneously corresponds to more realistic working conditions for the enzyme. Taking the inactive variant of LCCICCG as an example, we compare spectral quality at 30{degrees}C and 50{degrees}C, and find that the latter condition greatly improves the Signal-to-Noise (S/N) ratio of the standard triple resonance spectra. Going up to 60{o}C, we show that pulse sequences mainly used for the assignment of intrinsically disordered proteins (IDPs) also become feasible. As a result, we present a methodology enabling exhaustive backbone assignment based on a minimal set of triple resonance spectra acquired and analysed in less than two weeks. The assignment process hence can be completed on a time scale comparable to crystallography, bringing NMR in a favourable position to contribute to bio-structural studies on this family of highly thermostable PETases.

biophysics↗

bioRxiv2022

An iterative gene editing strategy broadens eIF4E1 genetic diversity in Solanum lycopersicum and generates resistance to several potyvirus isolates

Resistance to potyviruses in plants have been largely provided by the selection of natural variant alleles of eukaryotic initiation factors (eIF) 4E in many crops. However, the sources of such variability for breeding can be limited for certain crop species, while new virus strains continue to emerge. Different methods of mutagenesis have been applied to inactivate the eIF4E genes to generate virus resistance, but with limited success due to the physiological importance of translation factors and their redundancy. Here, we employed genome editing approaches at the base level to induce non-synonymous mutations in the eIF4E1 gene and create genetic diversity in cherry tomato (Solanum lycopersicum var. cerasiforme). We sequentially edited the genomic sequences coding for two regions of eIF4E1 protein, located around the cap-binding pocket and known to be important for susceptibility to potyviruses. We show that the editing of only one of the two regions, by gene knock-in and base-editing, respectively, is not sufficient to provide resistance. However, combining amino acid mutations in both regions resulted in resistance to multiple potyviruses without affecting its functionality in translation initiation. Meanwhile, we report that extensive base editing in exonic region can alter RNA splicing pattern, resulting in gene knockout. Altogether our work demonstrates that precision editing allows to design plant factors based on the knowledge on evolutionarily selected alleles and enlarge the gene pool to potentially provide advantageous phenotypes such as pathogen resistance.

plant biology↗