Identification and characterization of the AcrR/AcrAB system of a pathogenic Edwardsiella tarda strain

The Journal of General and Applied Microbiology

Min Zhang¹  Jin-hui Hou¹  Li Sun¹  Yong-hua Hu¹ 

[1] Institute of Oceanology, Chinese Academy of Sciences

关键词: AcrAB;    acriflavine;    AcrR;    antimicrobial resistance;    methyl viologen;    virulence;   

DOI  :  10.2323/jgam.55.191

学科分类：微生物学和免疫学

来源: Applied Microbiology, Molecular and Cellulrar Biosciences Research Foundation

【 摘 要 】

Edwardsiella tarda is one of the leading marine pathogens that can infect a wide range of cultured marine species. In this study, the acrR-acrAB cluster was cloned from TX1, a pathogenic E. tarda strain isolated from diseased fish. AcrR and AcrAB were found to be involved in resistance against acriflavine and methyl viologen, which positively regulate the expression of acrAB. AcrR negatively regulates its own expression and the expression of the acrAB operon, most likely by interacting with a 24-bp operator site that overlaps the putative promoter of acrA (PacrA). The repressive effect of AcrR on PacrA could be relieved by acriflavine, methyl viologen, and ethidium bromide, the presence of each of which enhanced transcription from PacrA. Interruption of the regulated expression of acrR by introducing into TX1 a plasmid that overexpresses acrR affected growth under stress conditions, AI-2 production, and bacterial virulence. In addition, mutational analyses identified a constitutively active AcrR mutant (named N215), which exhibits full repressor activity but is impaired in its ability to interact with the inducer. Overexpression of N215 produced the same kind of but moderately stronger effect on TX1 compared to that produced by overexpression of the wild-type acrR.

【 授权许可】

Unknown