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Updated: Jan 17, 2026

Super-Resolution Imaging of Bacterial Secreted Proteins Using Genetic Code Expansion
Published on: February 10, 2023
Emerging insights into the type I secretion system: a key player in Salmonella virulence and host-pathogen
Siqi Li1, Hongtao Liu1, Jiazhang Qiu1
1State Key Laboratory for Diagnosis and Treatment of Severe Zoonotic Infectious Diseases, Key Laboratory for Zoonosis Research of the Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China.
Abstract:
Salmonella spp. are major zoonotic bacterial pathogens that can cause a range of diseases in both humans and animals, including gastroenteritis, septicemia, and typhoid fever. During intestinal colonization, Salmonella relies on the coordinated action of the SPI-4 encoded type I secretion system (T1SS) and SPI-1 encoded type III secretion system (T3SS-1) to breach epithelial barriers. Although the T3SS-1 and its effectors have been widely studied, the T1SS and its associated effectors remain poorly characterized. The T1SS-secreted substrate SiiE binds to host cell surface mucins via its bacterial Ig-like (BIg) domain, facilitating the proper positioning of the T3SS-1 and subsequently triggering bacterial internalization. Given the critical role of the T1SS and SiiE in Salmonella virulence, they may serve as promising targets for anti-virulence drug development. In this review, we provide an overview of the current knowledge on the T1SS, including its regulatory mechanisms, channel formation, and the functional properties of SiiE.
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