ZFIN ID: ZDB-PUB-090706-11
Edwardsiella tarda T6SS component evpP is regulated by esrB and iron, and plays essential roles in the invasion of fish
Wang, X., Wang, Q., Xiao, J., Liu, Q., Wu, H., Xu, L., and Zhang, Y.
Date: 2009
Source: Fish & shellfish immunology   27(3): 469-477 (Journal)
Registered Authors: Liu, Qin
Keywords: Edwardsiella tarda, evpP, esrB, Iron, Invasion
MeSH Terms:
  • Animals
  • Bacterial Proteins/chemistry
  • Bacterial Proteins/metabolism*
  • Cell Line, Tumor
  • Edwardsiella tarda/genetics
  • Edwardsiella tarda/metabolism*
  • Edwardsiella tarda/pathogenicity*
  • Enterobacteriaceae Infections/microbiology
  • Enterobacteriaceae Infections/mortality
  • Enterobacteriaceae Infections/veterinary*
  • Fish Diseases/microbiology*
  • Fish Diseases/mortality
  • Flatfishes/microbiology
  • Hemolysis
  • Iron/metabolism*
  • Mucus/metabolism
  • Sequence Deletion
  • Virulence/genetics
  • Zebrafish/microbiology
PubMed: 19563898 Full text @ Fish Shellfish Immunol.
Edwardsiella tarda is a gram-negative pathogen for hemorrhagic septicemia in a broad range of hosts. The type VI secretion system (T6SS) has recently been dissected in E. tarda to secrete EvpC, EvpI and a novel effector protein EvpP. In this study, sequencing and genetic alignments showed that evpP genes from different E. tarda isolates were highly similar and an evpP homolog was also found in Aeromonas hydrophila 0865 isolated from a diseased eel, suggesting the possible lateral gene transfer of evpP or the whole T6SS gene island. With reporter strains carrying gfp gene fused to the evpP promoter region, flow cytometric analysis revealed that transcription of evpP was positively regulated by either the two-component system EsrA-EsrB in E. tarda or the iron concentration in media. Compared with the parental strain, in-frame deletion of evpP in E. tarda EIB202 led to the significantly increased 50% lethal doses in zebrafish (Danio rerio) and Japanese flounder (Paralichthys olivaceus), decreased hemolytic activities, failure to adhere to mucus and reduced serum resistance, and complementation of an intact evpP gene restored these phenotypes in the evpP mutant. Investigation of infection kinetics indicated that the evpP deletion mutant was unable to proliferate in vivo, particularly in immune organs of fish. Moreover, the evpP deletion mutant exhibited incapacity to internalize in EPC cell model in vitro, demonstrating that EvpP in T6SS plays critical roles for invasion mechanism of E. tarda and merits as potential target for attenuated live vaccine construction.