Proteolysis in Plants

Extraction of ubiquitinated proteins from chloroplasts in CHLORAD is driven by the cytosolic ATPase Cdc48. The UBX-domain protein PUX10 is shown to be a CHLORAD component that recruits Cdc48 to the chloroplast surface.

Chromosomal patterning of meiotic crossovers is mediated by pro-crossover HEI10 E3 ligase dynamics. This study reveals that a network of HSP40–HSP70 chaperones facilitates HEI10 proteolysis, thereby limiting formation of closely spaced crossovers.

Phytophthora secretes a conserved trypsin-like serine protease, PsTry1, that suppresses apoplastic immunity by cleaving the extracellular domain of the co-receptor BAK1, revealing a novel mechanism by which pathogens overcome apoplastic immune defences.

GI forms an inactive nuclear condensate that is dispersed at high temperatures by FKF1 binding to GI’s intrinsically disordered region. The resulting FKF1–GI complex promotes SVP degradation, accelerating flowering at high ambient temperatures.

PRT1 is an E3 ligase that recognizes type-2 hydrophobic aromatic Arg/N-degrons. Here, the authors reveal the structure of the ZZ domain of Arabidopsis PRT1 bound to bulky hydrophobic type-2 N-degrons, showing a unique binding site formed by a substantial conformational change of two loops and uncovering an intramolecular tandem RING dimer essential for its ubiquitylation activity.

Extracellular proteasomes are found in the Arabidopsis apoplastic fluid and shown to participate in biotic defense by proteolytically digesting pathogen proteins into microbe-associated molecular pattern epitopes specifically recognized by the pathogen-triggered innate immune response system.

Li et al. found that heat stress induces the translocation of upstream autophagy proteins to stress granules, revealing the molecular mechanisms by which heat stress enhances autophagy activity.

Arabidopsis metacaspase 9 (AtMC9) regulates plant development and immunity via pH-dependent activation. Here, the authors use crystal structures, simulations, and assays to show glutamate and histidine residues control AtMC9 activity, providing insights for enhancing crop immunity and yield.

This study demonstrates that the adaptor protein AP-3β recruits the 19S regulatory particle (RP) of the proteasome to stress granules (SGs) after heat stress and promotes SG disassembly through RP-associated deubiquitylation process.

The analysis of the function of acylamino acid-releasing enzymes (AARE) in Physcomitrella and Arabidopsis reveals a connection between AARE and plant ageing, suggesting a unified concept of ageing may exist across domains of life.

Examination of the cell fate gene-regulatory networks of the moss Physcomitrium patens reveals regulons that exhibit misregulation in mutants for the calpain DEFECTIVE KERNEL1 (DEK1) gene.