Unraveling and characterization of novel T3SS effectors in Edwardsiella piscicida

作者：Xiao Jian Liao, Tian Tian He, Lu Yi Liu, Xiu Long Jiang, Shan Sun, Yu Hang Deng, Li Qiang Zhang, Hai Xia Xie, Pin Nie · 发表于：mSphere · 年份：2023 · DOI：10.1128/msphere.00346-23 · 被引用次数：11 · 研究领域：Aquaculture disease management and microbiota、Invertebrate Immune Response Mechanisms、interferon and immune responses

ABSTRACT Type III secretion system (T3SS) facilitates survival and replication of Edwardsiella piscicida in vivo . Identifying novel T3SS effectors and elucidating their functions are critical in understanding the pathogenesis of E. piscicida. E. piscicida T3SS effector EseG and EseJ was highly secreted when T3SS gatekeeper-containing protein complex EsaB-EsaL-EsaM was disrupted by EsaB deficiency. Based on this observation, concentrated secretomes of Δ esaB strain and Δ esaB Δ esaN strain were purified by loading them into SDS-PAGE gel for a short electrophoresis to remove impurities prior to the in-the gel digestion and mass spectrometry. Four reported T3SS effectors and two novel T3SS effector candidates EseQ (ETAE_2009) and Trx2 (ETAE_0559) were unraveled by quantitative comparison of the identified peptides. EseQ and Trx2 were revealed to be secreted and translocated in a T3SS-dependent manner through CyaA-based translocation assay and immunofluorescent staining, demonstrating that EseQ and Trx2 are the novel T3SS effectors of E. piscicida . Trx2 was found to suppress macrophage apoptosis as revealed by TUNEL staining and cleaved caspase-3 of infected J774A.1 monolayers. Moreover, Trx2 has been shown to inhibit the p65 phosphorylation and p65 translocation into the nucleus, thus blocking the NF-κB pathway. Furthermore, depletion of Trx2 slightly but significantly attenuates E. piscicida virulence in a fish infection model. Taken together, an efficient method was establis...