Every step you take: How pathogens hijack host proteostasis from transcription, through translation, to degradation

Proteostasis, the regulated balance between protein synthesis and degradation, is crucial for the cellular function and survival. Disruptions in this balance caused by different internal cues and environmental stresses, including pathogen infection, lead to proteotoxicity, which can be highly detrimental or even lethal to the organisms. Pathogens, in their efforts to modulate the host physiology to accommodate their own needs, target and manipulate host proteostasis processes. The extent of pathogen-mediated manipulation of host proteostasis spans every step in the life cycle of a protein: from the transcription and maturation of its coding mRNA, to the protein turnover via the ubiquitin-proteasome system or vacuolar degradation. These diverse sophisticated strategies to manipulate the host proteostasis ultimately lead to the overaccumulation of unfunctional and misfolded proteins, causing proteotoxic stress and facilitating in most cases the pathogen colonization. In turn, plants try to cope with this pathogen-induced proteotoxicity by attenuating translation, promoting chaperon-assisted protein folding and increasing the activity of different proteolytic pathways. Here, we discuss recent advances in understanding the global picture of how pathogens modulate plant proteostasis as well as how plants counter this, which will be crucial for the future development of more tolerant crops to mitigate emerging food security threats.