Identification and Characterization of EvpQ, a Novel T6SS Effector Encoded on a Mobile Genetic Element in Edwardsiella piscicida

Abstract

In this study, a hypothetical protein (ORF02740) secreted by Edwardsiella piscicida was identified. We renamed the ORF02740 protein as EvpQ, which is encoded by a mobile genetic element (MGE) in E. piscicida genome. The evpQ gene is spaced by 513 genes from type VI secretion system (T6SS) gene cluster. Low GC content, three tRNA, and three transposase genes nearby evpQ define this MGE that evpQ localizes as a genomic island. Sequence analysis reveals that EvpQ shares a conserved domain of C70 family cysteine protease and shares 23.91% identity with T3SS effector AvrRpt2 of phytopathogenic Erwinia amylovora. Instead, EvpQ of E. piscicida is proved to be secreted at a T6SS-dependent manner, and it can be translocated into host cells. EvpQ is thereof a novel T6SS effector. Significantly decreased competitive index of ΔevpQ strain in blue gourami fish (0.53 ± 0.27 in head kidney and 0.44 ± 0.19 in spleen) indicates that EvpQ contributes to the pathogenesis of E. piscicida. At 8-, 18-, and 24-h post-subculture into DMEM, the transcription of evpQ was found to be negatively regulated by Fur and positively regulated by EsrC, and the steady-state protein levels of EvpQ are negatively controlled by RpoS. Our study lays a foundation for further understanding the pathogenic role of T6SS in edwardsiellosis.

Sporulation Activated via σ W Protects Bacillus from a Tse1 Peptidoglycan Hydrolase Type VI Secretion System Effector

“…Upstream of vgrG is hcp , which encodes a structural component essential for T6SS function. Tse5 is a putative cysteine protease, likely having a function similar to that of an effector recently described in Edwardsiella piscicida ( 46 ). Tse6 contains two uncharacterized DUF4112 domains in its N terminus, similar to those found primarily in Acinetobacter strains.…”

Sporulation activated via σW protects Bacillus from a Tse1 peptidoglycan hydrolase T6SS effector

“…Downstream of vgrG is hcp , which encodes a structural component essential for T6SS function. Tse5 is a putative cysteine protease, likely having a function similar to that of an effector recently described in Edwardsiella piscicida (Li et al ., 2021). Tse6 contains two uncharacterized DUF4112 domains in its N-terminus, similar to those primarily found in Acinetobacter strains.…”

Edwardsiella tarda Attenuates Virulence upon Oxytetracycline Resistance

“…As an enteric pathogen, E. tarda normally adheres to and invades cells for proliferation, which is dependent on T3SS and T6SS. , LTB4-S and LTB4-R OTC were incubated with EPC cells. The number of extracellular bacteria attached to the EPC cells was quantified after 30 min of incubation, representing bacterial adhesion.…”