Arginine GlcNAcylation of Rab small GTPases by the pathogen Salmonella Typhimurium

Xing Pan,Zhen Wang,Feng Shao,Ting Peng,Shufan Hu,Jin Yang,Xiaohui Zhuang,Kun Meng,Shan Li,Juan Xue,Jun Lv,Xiaoyun Liu,Jiaqi Fu

doi:10.1038/s42003-020-1005-2

Abstract

Salmonella enterica serovar Typhimurium, an intracellular Gram-negative bacterial pathogen, employs two type III secretion systems to deliver virulence effector proteins to host cells. One such effector, SseK3, is a Golgi-targeting arginine GlcNAc transferase. Here, we show that SseK3 colocalizes with cis-Golgi via lipid binding. Arg-GlcNAc-omics profiling reveals that SseK3 modifies Rab1 and some phylogenetically related Rab GTPases. These modifications are dependent on C-termini of Rabs but independent of the GTP- or GDP-bound forms. Arginine GlcNAcylation occurs in the switch II region and the third α-helix and severely disturbs the function of Rab1. The arginine GlcNAc transferase activity of SseK3 is required for the replication of Salmonella in RAW264.7 macrophages and bacterial virulence in the mouse model of Salmonella infection. Therefore, this SseK3 mechanism of action represents a new understanding of the strategy adopted by Salmonella to target host trafficking systems.

Highlights

Salmonella enterica serovar Typhimurium, an intracellular Gram-negative bacterial pathogen, employs two type III secretion systems to deliver virulence effector proteins to host cells
Rab GTPases switch between two distinct conformational states, the active GTP-bound form and the inactive GDP-bound form, regulated by guanine nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs)
Typhimurium pathogenesis is highly dependent on two type III secretion systems (T3SS) that are encoded within the pathogenicity islands 1 (SPI-1) and 2 (SPI-2), which function in the transport of bacterial effector proteins to the cytoplasm of the host cell[9]

Summary

Introduction

Salmonella enterica serovar Typhimurium, an intracellular Gram-negative bacterial pathogen, employs two type III secretion systems to deliver virulence effector proteins to host cells. One such effector, SseK3, is a Golgi-targeting arginine GlcNAc transferase. The arginine GlcNAc transferase activity of SseK3 is required for the replication of Salmonella in RAW264.7 macrophages and bacterial virulence in the mouse model of Salmonella infection This SseK3 mechanism of action represents a new understanding of the strategy adopted by Salmonella to target host trafficking systems. SseK3, but not SseK1, can modify a set of Rab GTPases, including Rab[1] and some phylogenetically related Rab proteins, through arginine GlcNAcylation This modification is dependent on the C-terminal prenylation of Rab[1] but independent of the GTP- or GDP-bound forms. SseK3 blocks the host inflammatory cytokine secretion during Salmonella infection and is crucial for bacterial virulence in mice

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Results

Conclusion