Work

The ubiquitin system targets translocated EspH to proteasomal degradation

Year: 2025

Type: article

Abstract: EspH is an effector protein secreted by the type III secretion system of various pathogenic Escherichia coli strains, including enteropathogenic E. coli (EPEC). The ability of EspH to inhibit host RhoGTPases, disrupt the actin cytoskeleton, and induce host cell cytotoxicity has been well-documented. Mass spectrometry analysis of EspH translocated into EPEC-infected cells revealed that a lysine at position 106 (K106) is modified with ubiquitin. Immunoblotting using the FK2 anti-ubiquitin antibodies has confirmed these results, suggesting that EspH undergoes polyubiquitylation. Prediction algorithms have identified a single ubiquitylation site at K106 and a phosphodegron in EspH. Moreover, we show that wild-type (EspHwt), but not the EspHK106R mutant, is subjected to degradation following translocation in an MG132-sensitive manner, indicating that the proteasome degrades the polyubiquitylated effector following translocation. Finally, we show that translocated EspHK106R induces higher cytotoxicity than translocated EspHwt. EspHwt translocated into MG132-pretreated cells also displayed higher cytotoxicity levels than EspHwt in untreated cells. These data reinforce the idea that EspH is polyubiquitylated and that the host proteasome degrades the translocated effector, possibly limiting its ability to toxicate the host cells. Additional implications of these effects on bacterial-host interactions are discussed.

Source: Gut Microbes

DOI: 10.1080/19490976.2025.2595775

Authors: Ipsita Nandi, Efrat Zlotkin-Rivkin, Hanan Schoffman, Benjamin Aroeti

Institution: Hebrew University of Jerusalem

Language: English

Topic: Escherichia coli research studies

Subfield: Endocrinology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: gold

Estimated APC paid: $3,060