YopK regulates the Yersinia pestis type III secretion system from within host cells

Abstract

Summary The pathogenic Yersinia species share a conserved type III secretion system, which delivers cytotoxic effectors known as Yops into target mammalian cells. In all three species, YopK (also called YopQ) plays an important role in regulating this process. In cell culture infections, yopK mutants inject higher levels of Yops, leading to increase cytotoxicity; however, in vivo the same mutants are highly attenuated. In this work, we investigate the mechanism behind this paradox. Using a β-lactamase reporter assay to directly measure the effect of YopK on translocation, we demonstrated that YopK controls the rate of Yop injection. Furthermore, we find that YopK cannot regulate effector Yop translocation from within the bacterial cytosol. YopE is also injected into host cells and was previously shown to contribute to regulation of the injectisome. In this work we show that YopK and YopE work at different steps to regulate Yop injection, with YopK functioning independently of YopE. Finally, by expressing YopK within tissue culture cells, we confirm that YopK regulates translocation from inside the host cell, and we show that cells pre-loaded with YopK are resistant to Yop injection. These results suggest a novel role for YopK in controlling the Yersinia type III secretion system.

Protein Export According to Schedule: Architecture, Assembly, and Regulation of Type III Secretion Systems from Plant- and Animal-Pathogenic Bacteria

“…Inhibition of pore formation was also shown for the cysteine protease YopT, which cleaves Rho GTPases, as well as for the effector protein YopK (141,225,361,500,572,640). Furthermore, an increase in the size of the translocation pore was observed for mutants of Salmonella spp.…”

Genome-Wide Analysis of Small RNAs Expressed by Yersinia pestis Identifies a Regulator of the Yop-Ysc Type III Secretion System

“…It is regulated in a specific, multilayered manner to ensure that effectors are synthesized and secreted only when their delivery to host cells is needed. In addition, Yersinia, through the action of YopK, ensures that only a certain amount of effectors is delivered to each cell (74). Within this framework, then, it is not surprising that sRNAs participate in the regulation of effector production.…”

Shigella IpaH7.8 E3 ubiquitin ligase targets glomulin and activates inflammasomes to demolish macrophages

“…Some bacterial pathogens, such as S. typhimurium (22) and Yersinia pseudotuberculosis (23)(24)(25), can induce macrophage death after they have fully replicated, promoting the egress of bacteria from their replicative compartments and the subsequent dissemination of bacteria into new host cells. This causal relationship suggests that these pathogens may benefit from and exert control over host cell death and the inflammatory response.…”

“…Interestingly, the mode through which NLRs recognize Shigella infections seems to vary across different infection conditions. At a low infectious dose [e.g., a multiplicity of infection (MOI) of [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25], bacteria induce rapid NLRC4-caspase-1-dependent pyroptosis at 2-3 h postinfection through the recognition of the T3SS components or some uncharacterized T3SS-delivered substance(s) (19,22). However, at a high infectious dose (e.g., an MOI over 50) and at later time points (6 h postinfection), the bacteria induce NLRP3-dependent but caspase-1-independent necrosis-like cell death with inflammation (called "pyronecrosis") (8).…”