Salmonella Typhimurium effector SseI regulates host peroxisomal dynamics to acquire lysosomal cholesterol

鼠伤寒沙门氏菌效应子 SseI 调节宿主过氧化物酶体动力学以获取溶酶体胆固醇

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作者:Desh Raj, Abhilash Vijay Nair, Anmol Singh, Swarnali Basu, Kabita Sarkar, Jyotsna Sharma, Shiva Sharma, Sanmi Sharma, Manisha Rathore, Shriya Singh, Shakti Prakash, Simran, Shikha Sahu, Aman Chandra Kaushik, Mohammad Imran Siddiqi, Uday C Ghoshal, Tulika Chandra, Vivek Bhosale, Arunava Dasgupta, Sha

Abstract

Salmonella enterica serotype Typhimurium (Salmonella) resides and multiplies intracellularly in cholesterol-rich compartments called Salmonella-containing vacuoles (SCVs) with actin-rich tubular extensions known as Salmonella-induced filaments (SIFs). SCV maturation depends on host-derived cholesterol, but the transport mechanism of low-density lipoprotein (LDL)-derived cholesterol to SCVs remains unclear. Here we find that peroxisomes are recruited to SCVs and function as pro-bacterial organelle. The Salmonella effector protein SseI is required for the interaction between peroxisomes and the SCV. SseI contains a variant of the PTS1 peroxisome-targeting sequence, GKM, localizes to the peroxisomes and activates the host Ras GTPase, ADP-ribosylation factor-1 (ARF-1). Activation of ARF-1 leads to the recruitment of phosphatidylinsolitol-5-phosphate-4 kinase and the generation of phosphatidylinsolitol-4-5-bisphosphate on peroxisomes. This enhances the interaction of peroxisomes with lysosomes and allows for the transfer of lysosomal cholesterol to SCVs using peroxisomes as a bridge. Salmonella infection of peroxisome-depleted cells leads to the depletion of cholesterol on the SCVs, resulting in reduced SIF formation and bacterial proliferation. Taken together, our work identified peroxisomes as a target of Salmonella secretory effectors, and as conveyance of host cholesterol to enhance SCV stability, SIF integrity, and intracellular bacterial growth.

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