Bacterial effector restricts liquid-liquid phase separation of ZPR1 to antagonize host UPRER

How pathogens manipulate host UPRER to mediate immune evasion is largely unknown. Here, we identify the host zinc finger protein ZPR1 as an interacting partner of the enteropathogenic E. coli (EPEC) effector NleE using proximity-enabled protein crosslinking. We show that ZPR1 assembles via liquid-liquid phase separation (LLPS) in vitro and regulates CHOP-mediated UPRER at the transcriptional level. Interestingly, in vitro studies show that the ZPR1 binding ability with K63-ubiquitin chains, which promotes LLPS of ZPR1, is disrupted by NleE. Further analyses indicate that EPEC restricts host UPRER pathways at the transcription level in a NleE-ZPR1 cascade-dependent manner. Together, our study reveals the mechanism by which EPEC interferes with CHOP-UPRER via regulating ZPR1 to help pathogens escape host defense. [Display omitted] •Screen transiently interacting partners of effectors under physiological conditions•Great potential of chemical crosslinkers in basic research•Pathogen attenuates host UPRER dependent on the NleE-ZPR1 cascade•ZPR1 undergoes liquid-liquid phase separation (LLPS) and regulates transcription Ouyang et al. explore the potential and strength of chemical crosslinkers, capture transient interactions between substrate and enzyme, highlight possible mechanisms and functions of ZPR1 liquid-liquid phase separation, and reveal a mechanism by which bacterial pathogen attenuates UPRER in an NleE-ZPR1-dependent manner.