Numero 166

Cari socie e soci,

continuiamo con il terzo appuntamento dei nostri VIRTUAL CLUB SIBV, una serie di webinar dedicati a giovani studenti, dottorandi e ricercatori.

Il terzo seminario si svolgerà il 07 luglio 2022 dalle ore 17:00 alle ore 18:00 e sarà svolto dal Dott. Jacopo Rossi dell’Università degli Studi di Bologna.

S-nitrosylation homeostasis in plants: key enzymes and regulatory pathways
The nitrosylated form of glutathione (GSNO) has been acknowledged to be the most important nitrosylating agent of the plant cell, and the tuning of its intracellular concentration is of pivotal importance for photosynthetic life. Hence, it is pivotal to understand the enzymatic systems involved in the degradation of GSNO. During my time as a PhD student, I decided to study the structural and catalytic features of alcohol dehydrogenases (GSNOR and ADH1) from the model land plant Arabidopsis thaliana (At). These enzymes displayed a very similar 3D structure except for their active site which might explain the extreme catalytic specialization of the two enzymes. They share NAD(H) as a cofactor, but only AtGSNOR was able to catalyze the reduction of GSNO whilst being ineffective in oxidizing ethanol. Moreover, the enzyme from the unicellular green alga Chlamydomonas reinhardtii (Cr) revealed how this S-nitrosoglutathione reductase (GSNOR) specifically use NADH to catalyze GSNO reduction and how its activity responds to thiol-based posttranslational modifications. Contextually, the presence of NADPH-dependent GSNO-degrading systems in algal protein extract was highlighted and resulted to be relatively efficient in this model organism. This activity could be ascribed to several proteins whose contribution has not been defined yet. Intriguingly, protein extract from GSNOR null mutants of Arabidopsis displayed an increased NADPH-dependent ability to degrade GSNO and our quantitative proteome profiling on the gsnor mutant revealed the overexpression of two class 4 aldo-keto reductases (AKR), specifically AtAKR4C8 and AtAKR4C9. Later, all four class 4 AKRs showed to possess a NADPH-dependent GSNOdegrading activity. Finally, preliminary analysis revealed the kinetic parameters of several plant proteins, including GSNOR, AKR4Cs, and thioredoxins. These data suggested GSNOR to be the most effective enzyme in catalyzing GSNO reduction because of its extremely high catalytic proficiency compared to NADPH-dependent systems.

Ciascuna sessione dei Virtual Club sarà svolta attraverso l’uso della Piattaforma Microsoft Teams.

Informazioni relative alle prossime sessioni sono presenti sul sito (clicca qui)

Per ulteriori informazioni non esitate a contattarci inviandoci una e-mail all’indirizzo segretario@sibv.eu

Ci auguriamo ed auspichiamo una grande partecipazione tra i soci ed interazione con gli speaker al fine di rendere questi momenti di incontro virtuale una preziosa occasione per la crescita della nostra comunità,

Un caro saluto

Il Presidente, Laura De Gara                                                                  Il Segretario, Sara Cimini

*******************************************************

Dear SIBV members and associates,

we are ready for the third seminar of our VIRTUAL CLUB SIBV, a series of webinars dedicated to young students, PhD students and researchers.

The third seminar will take place on July 07, 2022 from 17:00 to 18:00 and will be held by Dott. Jacopo Rossi of the University of Bologna.

S-nitrosylation homeostasis in plants: key enzymes and regulatory pathways
The nitrosylated form of glutathione (GSNO) has been acknowledged to be the most important nitrosylating agent of the plant cell, and the tuning of its intracellular concentration is of pivotal importance for photosynthetic life. Hence, it is pivotal to understand the enzymatic systems involved in the degradation of GSNO. During my time as a PhD student, I decided to study the structural and catalytic features of alcohol dehydrogenases (GSNOR and ADH1) from the model land plant Arabidopsis thaliana (At). These enzymes displayed a very similar 3D structure except for their active site which might explain the extreme catalytic specialization of the two enzymes. They share NAD(H) as a cofactor, but only AtGSNOR was able to catalyze the reduction of GSNO whilst being ineffective in oxidizing ethanol. Moreover, the enzyme from the unicellular green alga Chlamydomonas reinhardtii (Cr) revealed how this S-nitrosoglutathione reductase (GSNOR) specifically use NADH to catalyze GSNO reduction and how its activity responds to thiol-based posttranslational modifications. Contextually, the presence of NADPH-dependent GSNO-degrading systems in algal protein extract was highlighted and resulted to be relatively efficient in this model organism. This activity could be ascribed to several proteins whose contribution has not been defined yet. Intriguingly, protein extract from GSNOR null mutants of Arabidopsis displayed an increased NADPH-dependent ability to degrade GSNO and our quantitative proteome profiling on the gsnor mutant revealed the overexpression of two class 4 aldo-keto reductases (AKR), specifically AtAKR4C8 and AtAKR4C9. Later, all four class 4 AKRs showed to possess a NADPH-dependent GSNOdegrading activity. Finally, preliminary analysis revealed the kinetic parameters of several plant proteins, including GSNOR, AKR4Cs, and thioredoxins. These data suggested GSNOR to be the most effective enzyme in catalyzing GSNO reduction because of its extremely high catalytic proficiency compared to NADPH-dependent systems.

Each Virtual Club session will be held via Microsoft Teams.

Information on upcoming sessions can be found on the SIBV website (click here)

For more information, do not hesitate to contact us by sending an e-mail to segretario@sibv.eu

We hope for great participation among the members and interaction with the speakers in order to make these moments of virtual meeting a precious opportunity for the growth of our community,

Warm greetings

Il Presidente, Laura De Gara                                                      Il Segretario, Sara Cimini