Just one week after our meeting in Málaga, from October 14–16, the Üstün lab was already back on the road — this time heading to Strasbourg for the International Plant Proteostasis Conference, organized by Pascal Genschik, Esther Lechner, and their colleagues at the IBMP. First of all, we want to thank all the people involved in the organization of great meeting during difficult times!
With only a few days between the two meetings, some of us had just enough time to squeeze in a load of laundry, while others enjoyed a slightly more relaxed travel schedule. But logistics aside, everyone was excited to attend. The conference is a real scientific highlight for the whole lab, bringing together almost all the topics we work on: from ubiquitination and autophagy to condensate-related mechanisms, all in the context of plant responses to abiotic and biotic stress.
While most of the team had attended previous PP meetings, for some of us this was our first chance to meet the wider plant proteostasis community in person. And we can confirm what we had heard before: it is a wonderfully welcoming, supportive, and genuinely enjoyable scientific community. Furthermore, we met our old colleague Gautier Langin, which is now a postdoc in the lab of Angelina Gross at BOKU in Vienna.
We set off on October 13 and, thanks to a few Deutsche Bahn–related adventures, arrived in Strasbourg a bit later than expected in the early afternoon. Hence, we still had time to explore the beautiful city and to get a taste of some of its culinary delights (tarte flambé of course and some local wines) before the scientific program kicked off the following morning. Despite initial uncertainties due to student protests in France, which were also happening in Strasbourg, the conference started smoothly. With so many exciting talks on plant proteostasis, we could hardly cover them all — so here are just a few of the many highlights that particularly caught our attention.
The conference started with a very strong session on E3 ligases and DUBs, with an invited talk by Nitzan Shabek who talked about his work on using proximity labelling-based proteomics to map SCF E3 adapter proxitomes under biotic and abiotic stress conditions. These approaches led to the discovery of a feedback mechanism around the phytohormone salicylic acid, which controls the expression and turnover of two SA-catabolic enzymes via the UPS [1].
Dan Gibbs presented his work on TOR–NOT4 signaling and protein quality control also including data, which stem from members of our group [2]. He reported that NOT4 proteins are involved in regulating translation in plants. In not4 mutants, TOR activity and protein synthesis are increased, and more ubiquitinated proteins accumulate. Interestingly, these mutants also showed higher resistance to bacterial infection.
The session also featured a rather unexpected last-minute speaker: none other than our very own Manuel González-Fuente. He presented his work on how bacterial effectors hijack plant processing bodies for their own benefit [3]. Manuel only learned about the opportunity the afternoon before, while enjoying a family vacation, and ended up putting the finishing touches on his presentation late that night in our, let’s say, less-than-luxurious AirBnB kitchen. Despite the rather unconventional preparation conditions and limited time, he delivered a great talk.
The day wrapped up with a session on the Proteasome and other proteases chaired by Şuayb, featuring plenty of interesting talks. Among them was Emmanuelle Graciet, who investigates the conservation of the N-degron pathway in Brassicaceae [4]. Her work revealed surprisingly crop-specific functions of the arginine transferases and E3 ligases involved in this pathway. Her talk was a great reminder that we should never assume that what we learn from our favourite model plant translates directly to crop species. Exploring these differences can lead to some surprising discoveries while limited genetic resources and molecular tools can make investigating these systems quite a challenge.
The Üstün lab was also represented in this session by Margot Raffeiner, who delivered a great and well-timed talk. She presented her work on the ubiquitin-binding aspartyl protease DDI1 and its role in mediating proteotoxic stress and plant immunity. Furthermore, Margot’s research also points to a role for this protease in responses to abiotic stresses, suggesting that its contribution to plant stress management extends well beyond immunity.
Kicking off the Proteolysis in plant immunity and pathogen interaction session, Steven Spoel took us on a journey through the fascinating world of ubiquitin-chain topologies, reminding us that while we know quite a bit about some of their functions, many remain a mystery waiting to be solved. His group tackles this challenge using topology-specific IP-MS approaches to map the interactomes associated with individual ubiquitin chains. Using these approaches, they recently discovered, that in response to pathogenic bacteria, RNA helicase 3 binds ubiquitinated ZAR1 and helps recruit it to receptor complexes involving BIK1, thereby potentiating PTI during effector-triggered immunity ETI [5].
Representing another branch of the Üstün lab, Shanshuo Zhu presented her fantastic work using single-cell RNA sequencing to investigate the cell-type-specific functions of autophagy in leaves during bacterial infection [6]. Her findings revealed that autophagy controls quite different mechanisms depending on which cells it operates in. In guard cells, it modulates multiple processes associated with ABA-mediated stomatal closure, while in the mesophyll, it appears to keep immune activation in check while simultaneously supporting the effective execution of immune responses.
Phase-separation and biomolecular condensates in the context of stress responses and proteostasis have become a main axis of the Üstün lab, hence we would also highlight some talks focusing on these topics. Panagiotis N. Moschou presented his research on RNA granules and temperature responses. He showed that temperature changes can trigger the disassembly of RNA granules inside P-bodies through the degradation of scaffold proteins, while the stored mRNAs are released rather than degraded.
Nuria Sanchez Coll discussed the role of metacaspase MC1 in stress-induced condensate regulation and its connection with the chaperone HSP101 during heat stress. Her group also found that in rice, a pseudometacaspase forms condensate during Magnaporthe infection modulating translation, suggesting that metacaspase-like proteins have yet undiscovered additional functions in plants.
Since we are already talking about condensates, we just briefly want to mention that us, the latest additions to the lab both presented posters on our P-body-focused projects, in the context of ABA responses and translation control, and the potential role of DIP1 in P-body homeostasis, which offered us lots of nice conversation and feedback.
While we feel we could highlight so much more talks here due to the density of the quality, we will conclude with some words on the regarding the programme points of the conference. The organizers had also arranged a guided boat trip for the entire conference community, giving us the chance to explore Strasbourg from a different perspective. Cruising through the city, we passed both the historic old town, like Le Petite France small and its more modern sites including the ARTE headquarter or the European Parliament while learning about the city’s history and local culture.
The day continued with the conference dinner at a charming local restaurant, with an almost unlimited supply of tarte flambée and drinks. With plenty of delicious food, refreshing drinks, and great conversations, it was the nice way to bring everyone together.
Overall, the conference was a good experience for us. We learned about different research topics relevant to the lab, discussed our projects with other researchers and got some useful ideas for our future work.
The Üstün lab concluded the trip to France with a short lab retreat in the beautiful town of Colmar, not far from Strasbourg. We really enjoyed walking through its charming old town streets, with colourful traditional houses and lovely canals and had two nice evenings with good Turkish and French food, nice chats and with the Üstün Lab Taboo, which Şuayb had specifically designed for the weekend. Let’s just say our ability to describe and guess the topics and things we encounter in the lab every day could use some improvement. The short retreat was a nice way to end our trip and made the whole experience even more memorable.
Bye Thorben Krüger and Wentao Luo – The dynamic modernity of a new generation, framed by the elegance and beauty of another era.