Auto Arginine-GlcNAcylation Is Crucial for Bacterial Pathogens in Regulating Host Cell Death.

Juan Xue,Xiaobin Cai,Yang Fu,Ting Peng,Meimei Duan,Xueying Yi,Lijie Du,Xiaohui Zhuang,Xing Pan,Shan Li

doi:10.3389/fcimb.2020.00197

Abstract

Many Gram-negative bacterial pathogens utilize the type III secretion system (T3SS) to inject virulence factors, named effectors, into host cells. These T3SS effectors manipulate host cellular signaling pathways to facilitate bacterial pathogenesis. Death receptor signaling plays an important role in eukaryotic cell death pathways. NleB from enteropathogenic Escherichia coli (EPEC) and SseK1/3 from Salmonella enterica serovar Typhimurium (S. Typhimurium) are T3SS effectors. They are defined as a family of arginine GlcNAc transferase to modify a conserved arginine residue in the death domain (DD) of the death receptor TNFR and their corresponding adaptors to hijack death receptor signaling. Here we identified that these enzymes, NleB, SseK1, and SseK3 could catalyze auto-GlcNAcylation. Residues, including Arg13/53/159/293 in NleB, Arg30/158/339 in SseK1, and Arg153/184/305/335 in SseK3 were identified as the auto-GlcNAcylation sites by mass spectrometry. Mutation of the auto-modification sites of NleB, SseK1, and SseK3 abolished or attenuated the capability of enzyme activity toward their death domain targets during infection. Loss of this ability led to the increased susceptibility of the cells to TNF- or TRAIL-induced cell death during bacterial infection. Overall, our study reveals that the auto-GlcNAcylation of NleB, SseK1, and SseK3 is crucial for their biological activity during infection.

Highlights

Death receptor signaling plays an important role in the innate immune system (Park et al, 2007; Wilson et al, 2009; Giogha et al, 2014; Luo et al, 2015)
We and other groups have shown that an enteropathogenic Escherichia coli (EPEC) T3SS effector, NleB, possessed novel arginine GlcNAc transferase activity toward multiple death domain (DD)-containing proteins in the host, including tumor necrosis factor receptor 1 (TNFR1), TNFR1-associated death domain protein (TRADD), FAS-associated death domain protein (FADD), and receptor-interacting serine/threonine-protein kinase 1 (RIPK1) (Li et al, 2013; Pearson et al, 2013)
The automodification deficient mutants, NleB (4RA), SseK1 (3RA), and SseK3 (4RA), could not inhibit the death receptor signaling pathways (Figures 4D–F). These data suggest that the auto-arginine-GlcNAcylation of NleB, SseK1, and SseK3 is crucial for their biological activity during infection

Summary

Introduction

Death receptor signaling plays an important role in the innate immune system (Park et al, 2007; Wilson et al, 2009; Giogha et al, 2014; Luo et al, 2015) Hijacking this signaling pathway through type III secretion system (T3SS) effectors has been evolved to be a pathogen evasion strategy (Lu et al, 2015; Luo et al, 2015). We and other groups have shown that an enteropathogenic Escherichia coli (EPEC) T3SS effector, NleB, possessed novel arginine GlcNAc transferase activity toward multiple death domain (DD)-containing proteins in the host, including tumor necrosis factor receptor 1 (TNFR1), TNFR1-associated death domain protein (TRADD), FAS-associated death domain protein (FADD), and receptor-interacting serine/threonine-protein kinase 1 (RIPK1) (Li et al, 2013; Pearson et al, 2013). The glycosyltransferase activity of NleB is crucial for the colonization ability of A/E bacteria during infection in animal models (Li et al, 2013; Pearson et al, 2013; Scott et al, 2017; Ding et al, 2019)

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Conclusion