The natural herbicide rhein targets photosystem I.

The natural anthraquinone rhein has been identified as a novel herbicide with a potentially new mode of action using a generative AI system for functional molecules discovery. Its herbicidal activity was light-dependent and resulted in rapid burndown symptoms on leaves of treated plants. Rhein interferes with photosynthesis by acting as an electron diverter at the level of photosystem I (PSI).

Formation of protein complexes in crowded environments--from in vitro to in vivo.

Traditionally, biochemical studies are performed in dilute homogenous solutions, which are very different from the dense mixture of molecules found in cells. Thus, the physiological relevance of these studies is in question. This recognition motivated scientists to formulate the effect of crowded solutions in general, and excluded volume in particular, on biochemical processes.

Contrasting factors on the kinetic path to protein complex formation diminish the effects of crowding agents.

The crowded environment of cells poses a challenge for rapid protein-protein association. Yet, it has been established that the rates of association are similar in crowded and in dilute solutions. Here we probe the pathway leading to fast association between TEM1 β-lactamase and its inhibitor protein BLIP in crowded solutions.

Protein-binding dynamics imaged in a living cell.

Historically, rate constants were determined in vitro and it was unknown whether they were valid for in vivo biological processes. Here, we bridge this gap by measuring binding dynamics between a pair of proteins in living HeLa cells. Binding of a β-lactamase to its protein inhibitor was initiated by microinjection and monitored by Förster resonance energy transfer.

Common crowding agents have only a small effect on protein-protein interactions.

Studies of protein-protein interactions, carried out in polymer solutions, are designed to mimic the crowded environment inside living cells. It was shown that crowding enhances oligomerization and polymerization of macromolecules. Conversely, we have shown that crowding has only a small effect on the rate of association of protein complexes.

On the contribution of water-mediated interactions to protein-complex stability.

Protein-water interactions have long been recognized as a major determinant of chain folding, conformational stability, binding specificity and catalysis. However, the detailed effects of water on stabilizing protein-protein interactions remain elusive. A way to test experimentally the contribution of water-mediated interactions is by applying double mutant cycle analysis on pairs of residues that do not form direct interactions, but are bridged by water.