In a new study published in Cell, Ben Engel’s group at the Helmholtz Pioneer Campus in Munich lays the foundation for this ambitious endeavor, in collaboration with colleagues from the Technical University of Kaiserslautern
(Michael Schroda group), Philipps-University Marburg (Jan Schuller), LMU Munich
(Jörg Nickelsen group), Okayama University (Wataru Sakamoto group), McGill University (Mike Strauss), Ruhr-University Bochum (Till Rudack), and the Max Planck Institute of Biochemistry (Wolfgang Baumeister and Jürgen Plitzko groups).

“Photosynthesis is our ally in this fight”, says Dr. Engel. Thylakoid membranes inside cyanobacteria, algae, and plants convert the energy of sunlight into biochemical energy, which these photosynthetic organisms then use to remove CO₂ from the atmosphere and fix it into the sugar that feeds much of the life on Earth, including humans. “Most of the life on our planet depends on thylakoid membranes. Our group seeks to understand how these intricate membrane structures are assembled and remodeled in response to changing environmental conditions,” explains Dr. Engel.

Vesicle-inducing protein in plastids (VIPP1) co-evolved with thylakoid membranes and is highly conserved in all thylakoid-bearing photosynthetic organisms, from land crops to marine algae and cyanobacteria. While decades of studies have implicated VIPP1 in thylakoid biogenesis and homeostasis, it has remained a mystery how this key player exerts its essential functions.

“Most of the life on our planet depends on thylakoid membranes. Our group seeks to understand how these intricate membrane structures are assembled and remodeled in response to changing environmental conditions.”
- Dr. Ben Engel.

In their recent study, Dr. Engel’s group used cryo-electron microscopy to generate the first high-resolution structure of VIPP1. Combining this structural analysis with in vitro and in vivo functional assays revealed with exquisite detail how VIPP1 assembles into an interwoven protein coat that hydrolyzes nucleotides and shapes membranes. Intriguingly, VIPP1 is both structurally and functionally homologous to ESCRT-III proteins, which repair a variety of membranes in human cells. Next, the researchers used the state-of-the-art technique of cryo-electron tomography to image VIPP1 structures within the native cellular environments of cyanobacteria and algae cells. They designed single mutations that interfere with VIPP1’s ability to bind membranes and observed lethal thylakoid swelling under high-light stress, implicating VIPP1 membrane remodeling in thylakoid maintenance under changing environmental conditions. They also observed VIPP1-coated membranes connecting the chloroplast envelope with thylakoids, providing the “missing link” for how thylakoids are built from lipids synthesized in the envelope.

While further details remain to be uncovered, this study lays the structural foundation for a mechanistic understanding of VIPP1-mediated thylakoid biogenesis and stress resistance across the photosynthetic tree of life. The study’s key insights into the molecular mechanisms driving thylakoid remodeling expand the molecular toolbox for engineering crops that not only grow faster and better resist environmental stress, but also fix more atmospheric CO₂ to push back against climate change.

_{International Dream Team:  “Our study covers a lot of new ground using a wide variety of techniques,” says Ben Engel. “This was only possible thanks to close collaborations that reached across eight institutions and three continents. I am grateful to be part of such an amazing team!”  Left column (top to bottom): Michael Schroda, Jan Schuller, Mike Strauss. Second column: Tilak Kumar Gupta, Steffen Heinz. Third column: Jörg Nickelsen, Norikazu Ohnishi, Till Rudack. Fourth column: Wojciech Wietrzynski, Sven Klumpe, Ben Engel. Fifth column: Karin Gries, Wataru Sakamoto, Jürgen Plitzko.}

• Link to full publication
• Link to PR from collaboration partners:
  - Helmholtz Zentrum München