Biology subjects

Lurin, C.

Publications and source records attributed to Lurin, C..

3 recordsLinked to original sources

bioRxiv2024

Dissecting the molecular puzzle of the editosome core in Arabidopsis organelles

Over the last decade, the composition of the C-to-U RNA editing complex in embryophyte organelles has turned out to be much more complex than first expected. While PPR proteins were initially thought to act alone, significant evidences have clearly depicted a sophisticated mechanism with numerous protein-protein interaction involving PPR and non-PPR proteins. Moreover, the identification of specific functional partnership between PPRs also suggests that, in addition to the highly specific PPRs directly involved in the RNA target recognition, non-RNA-specific ones are required. Although some of them, such as DYW1 and DYW2, were shown to be the catalytic domains of the editing complex, the molecular function of others, such as NUWA, remains elusive. It was suggested that they might stabilize the complex by acting as a scaffold. We here performed functional complementation of the crr28-2 mutant with truncated CRR28 proteins mimicking PPR without the catalytic domain and show that they exhibit a specific dependency to one of the catalytic proteins DYW1 or DYW2. Moreover, we also characterized the role of the PPR NUWA in the editing reaction and show that it likely acts as a scaffolding factor. NUWA is no longer required for efficient editing of the CLB19 editing sites once this RNA specific PPR is fused to the DYW catalytic domain of its partner DYW2. Altogether, our results strongly support a flexible, evolutive and resilient editing complex in which RNA binding activity, editing activity and stabilization/scaffolding function can be provided by one or more PPRs.

plant biology↗

bioRxiv2022

Limiting etioplast gene-expression induces apical hook twisting during skoto-morphogenesis of Arabidopsis seedlings

When covered by a layer of soil, seedling development follows a dark-specific program (skoto-morphogenesis) consisting of small, non-green cotyledons, a long hypocotyl and an apical hook to protect meristematic cells. We recently highlighted the role played by mitochondria in the high energy-consuming reprogramming of Arabidopsis skoto-morphogenesis. Here, the role played by plastids, another energy supplying organelle, in skoto-morphogenesis is investigated. This study was conducted in dark conditions to exclude light signals so as to better focus on those produced by plastids. It was found that limitation of plastid gene-expression (PGE) induced an exaggerated apical hook bending. Inhibition of PGE was obtained at the level of transcription and translation using the antibiotics rifampicin and spectinomycin, respectively, as well as plastid RPOTP RNA polymerase mutants. Rifampicin-treated seedlings also showed expression induction of marker nuclear genes for mitochondrial stress, perturbation of the mitochondrial metabolism, increase of ROS levels and an augmented capacity of oxygen consumption by mitochondrial alternative oxidases (AOX). AOX enzymes act to prevent over-reduction of the mitochondrial electron transport chain. Previously, we reported that AOX1A, the main AOX isoform, was a key component in the developmental response to mitochondrial respiration deficiency. In this work, we suggest the involvement of AOX1A in the response to PGE dysfunction and propose the importance of signalling between plastids and mitochondria. Finally, it was found that seedling architecture reprogramming in response to rifampicin was independent of canonical organelle retrograde pathways and the ethylene signaling pathway. Significance statementIn underground germination conditions, seedling development follows a dark-specific program (skoto-morphogenesis) consisting of small and non-green cotyledons, a long hypocotyl and an apical hook to protect meristematic cells. We show that skoto-morphogenesis is reprogrammed when plastid gene expression is perturbed leading to an exaggeration of apical hook bending. We propose the involvement of the cooperation between plastids and mitochondria, the energy-supplying organelles of the cell.

plant biology↗

bioRxiv2019

EffectorK, a comprehensive resource to mine for pathogen effector targets in the Arabidopsis proteome

Pathogens deploy effector proteins that interact with host proteins to manipulate the host physiology to the pathogens own benefit. However, effectors can also be recognized by host immune proteins leading to the activation of defense responses. Effectors are thus essential components in determining the outcome of plant-pathogen interactions. Despite major efforts to decipher effector functions, our current knowledge on effector biology is scattered and often limited. In this study, we conducted two systematic large-scale yeast two-hybrid screenings to detect interactions between Arabidopsis thaliana proteins and effectors from two vascular bacterial pathogens: Ralstonia pseudosolanacearum and Xanthomonas campestris. We then constructed an interactomic network focused on Arabidopsis and effector proteins from a wide variety of bacterial, oomycete, fungal and animal pathogens. This network contains our experimental data and protein-protein interactions from 2,035 peer-reviewed publications (48,200 Arabidopsis-Arabidopsis and 1,300 Arabidopsis-effector protein interactions). Our results show that effectors from different species interact with both common and specific Arabidopsis targets suggesting dual roles as modulators of generic and adaptive host processes. Network analyses revealed that effector targets, particularly effector hubs and bacterial core effector targets, occupy important positions for network organization as shown by their larger number of protein interactions and centrality. These interactomic data were incorporated in EffectorK, a new graph-oriented knowledge database that allows users to navigate the network, search for homology or find possible paths between host and/or effector proteins. EffectorK is available at www.effectork.org and allows users to submit their own interactomic data. Author summaryPlant pests and diseases caused by bacteria, oomycetes, fungi or animals are threatening food security worldwide. Understanding how these pathogens infect and manipulate the host is key to develop sustainable crop resistance in the long term. Effector proteins are secreted by pathogens to subvert the host immune responses. The roles of several effector proteins have been described; however, it is yet poorly understood how effectors interact with host proteins at a global level. To address this issue, we have generated EffectorK, an interactive database focused on the model plant species Arabidopsis thaliana. This database contains manually curated Arabidopsis-effector protein interactions from the available literature on a wide variety of pathogens. It also contains new experimental data on effectors from two vascular pathogens: Ralstonia pseudosolanacearum and Xanthomonas campestris. This work integrates all the gathered knowledge over the last decades and allows to identify general patterns of how effectors interact with the host proteome. This knowledge is easily accessible and searchable at www.effectork.org.

plant biology↗