PhD defense: Jonathan Przybyla-Toscano

Jonathan Przybyla-Toscano, étudiant au sein de l’équipe Redox de l’unité, défendra publiquement sa thèse vendredi 3 février à 13h (amphi 7 FST).

Venez nombreux !

Vendredi 3 février, 13h, (Amphi 7, FST): Jonathan Przybyla-Toscano (IAM)

Functional analysis of NFU and ISCA: proteins involved in Fe-S cluster maturation in Arabidopsis thaliana mitochondria

Abstract: In plants, iron-sulfur (Fe-S) proteins are involved in crucial processes such as photosynthesis and respiration. The maturation of these proteins requires the de novo synthesis of their Fe-S clusters through dedicated assembly machineries. Plants have three Fe-S cluster assembly machineries, namely SUF, ISC and CIA, devoted to the maturation of plastidial, mitochondrial and nuclear or cytosolic proteins, respectively. During the mitochondrial Fe-S protein maturation, a [2Fe-2S] cluster is first assembled on the ISU scaffold protein then transferred to target proteins with the help of chaperones and various transfer proteins. If these steps are sufficient for the maturation of [2Fe-2S] proteins, a reductive coupling process of two [2Fe-2S] clusters is required for the maturation of [4Fe-4S] proteins. This conversion needs transfer proteins and an electrons donor, potentially the same ferredoxin which acts during the first step of the Fe-S cluster biogenesis for sulfur reduction. By combining molecular, biochemical and genetic approaches, the involvement of NFU and ISCA transfer protein and mitochondrial ferredoxin (mFDX) in the late transfer and conversion steps has been explored during this PhD project by using the Arabidopsis thaliana plant model. Yeast complementation experiments have demonstrated that plant NFU and ISCA proteins have functions similar to their respective orthologs, suggesting that these late steps are conserved. However, unlike yeast, the characterization of nfu mutant lines indicates that both proteins are essential for early embryonic development. At the molecular level, in vivo and in vitro approaches have shown an interaction between ISCA1a or ISCA1b and ISCA2, NFU4 and NFU5 but no interaction with the two mFDX whose participation in the late steps remains uncertain. The formation of ISCA1-ISCA2 holo-heterocomplexes has been confirmed by co-expression in E. coli and purification of recombinant proteins. Overall, the literature and results obtained here highlight a model where ISCA1/2 heterocomplexes would act immediately downstream of NFU proteins which would a minima allow [4Fe-4S] cluster maturation of the lipoate synthase. This sole partner could primarily explain the lethality of a nfu4 x nfu5 double mutant because the activity of several proteins central for the mitochondrial metabolism depends on lipoic acid.

Seminar: Stéphane Hacquard

Le séminaire de la semaine sera donné demain par Stéphane Hacquard (Max Plank Institute) et sera suivi d’une réunion scientifique, ouverte à tous, portant sur les recherches faites dans l’unité concernant les communautés microbiennes/microbiome.

Vendredi 20 janvier, 13h30 (LGEF) : Stéphane Hacquard (Max Plank Institute, Cologne)

« Dissecting the Multispecies Interaction Network at the Arabidopsis Root/Soil Interface »

Dear all,

The seminar of tomorrow will be given by Stephan Hacquard from the Max Plank Institute. After the seminar, we will have a scientific meeting on microbiome research done in the unit. This meeting is open to all.

Friday 20th of January, 1.30pm (LGEF) : Stéphane Hacquard (Max Plank Institute, Cologne)

« Dissecting the Multispecies Interaction Network at the Arabidopsis Root/Soil Interface »

Prix la Recherche: Kohler et al.

Prix La Recherche 2016 :

Environnement : La symbiose entre les champignons et les arbres

La publication : Annegret Kohler et al., Nature Genetics47, 4, 2015.

Le résultat : Ce papier décrit les modèles moléculaires de l’évolution des champignons mycorrhiziens mutualistes. La plupart des plantes sont intiment associés avec des champignons qui leur fournissent des nutriments en échange de sucres produits et libérés par leurs hôtes. En particulier, les arbres et les orchidées ne peuvent pas pousser sans les champignons. Ce partenariat sous-tend donc la plupart des écosystèmes. L’évolution de ce partenariat a ici été élucidée à travers l’étude du génome différents champignons mycorrhiziens et de certaines orchidées, qui ont été comparés au génome de plusieurs champignons saprophytes (non mycorrhiziens) qui grandissent sur de la matière organique morte.

Trois raisons de récompenser cette publication, par Jacqui Shykoff, de l’Université Paris-Sud, à Orsay, et Denis Faure, de l’Institut de biologie intégrative, à Gif-sur-Yvette :
–    C’est une recherche fondamentale sur l’association plantes-champignons qui structure la plupart des écosystèmes terrestres.
–    Elle élucide les mécanismes partagés avec leurs spécificités individuelles dans l’évolution répétée de ce partenariat entre champignons et plantes.
–    C’est une recherche sur les champignons, un sujet de recherche sous-estimé.

PLR2016

Seminar: A. Brune

The weekly seminar will be given by Andreas Brune from Max Planck Institute, Marburg. A. Brune is a specialist of  gut microbiota of termites. 

24th of November, 3 pm (LEGF, INRA campus): Andreas Brune 

“The gut microbiota of termites: ecological drivers and convergent evolution”

Seminar: B. Grimm

The weekly seminar will be given by Bernard Grimm from Humbolt University (Berlin). B. Grimm is a specialist of the regulation of chlorophyll regulation. 

18th of November, 1.30pm (Amphi 7, FST): Bernhard Grimm (Université Humboldt, Berlin)

“Multiple ways of posttranslational control of chlorophyll biosynthesis”

Seminar: H. Germain

A seminar will be given by Hugo Germain from the “Université Québec Trois Rivières”. The seminar entitled

“Plant cell perturbation caused by effectors: development of an investigative toolbox”

will be held the 21th of  octobre at 1.30pm in the LEGF meeting room