Insight into the AcrAB-TolC Complex Assembly Process Learned from Competition Studies

Antibiotics

Yinan Wei¹  Ling Yang¹  Ankit Pandeya¹  Thilini Abeywansha¹  Isoiza Ojo¹  Prasangi Rajapaksha¹ 

[1] Department of Chemistry, University of Kentucky, Lexington, KY 40506, USA;

关键词: RND pump;    dominant negative effect;    assembly;    protein-protein interaction;    mutation;   

DOI  :  10.3390/antibiotics10070830

来源: DOAJ

【 摘 要 】

The RND family efflux pump AcrAB-TolC in E. coli and its homologs in other Gram-negative bacteria are major players in conferring multidrug resistance to the cells. While the structure of the pump complex has been elucidated with ever-increasing resolution through crystallography and Cryo-EM efforts, the dynamic assembly process remains poorly understood. Here, we tested the effect of overexpressing functionally defective pump components in wild type E. coli cells to probe the pump assembly process. Incorporation of a defective component is expected to reduce the efflux efficiency of the complex, leading to the so called “dominant negative” effect. Being one of the most intensively studied bacterial multidrug efflux pumps, many AcrA and AcrB mutations have been reported that disrupt efflux through different mechanisms. We examined five groups of AcrB and AcrA mutants, defective in different aspects of assembly and substrate efflux. We found that none of them demonstrated the expected dominant negative effect, even when expressed at concentrations many folds higher than their genomic counterpart. The assembly of the AcrAB-TolC complex appears to have a proof-read mechanism that effectively eliminated the formation of futile pump complex.

【 授权许可】

Unknown