Abstract
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.
Document Type
Article
Publication Date
7-8-2021
Digital Object Identifier (DOI)
https://doi.org/10.3390/antibiotics10070830
Funding Information
This research was funded by NIH grant number 1R56AI137020, 1R21AI142063-01, NIH/NHLBI HL142640, and NIH/NIGMS GM132443, and NSF grant number CHE-1709381.
Repository Citation
Rajapaksha, Prasangi; Ojo, Isoiza; Yang, Ling; Pandeya, Ankit; Abeywansha, Thilini; and Wei, Yinan, "Insight into the AcrAB-TolC Complex Assembly Process Learned from Competition Studies" (2021). Chemistry Faculty Publications. 183.
https://uknowledge.uky.edu/chemistry_facpub/183
Notes/Citation Information
Published in Antibiotics, v. 10, issue 7, 830.
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).