A Major Facilitator Superfamily (MFS) Efflux Pump, SCO4121, from Streptomyces coelicolor with Roles in Multidrug Resistance and Oxidative Stress Tolerance and Its Regulation by a MarR Regulator

Abstract

Overexpression of efflux pumps is one of the major determinants of resistance in bacteria. Streptomyces harbor a large array of efflux pumps that are transcriptionally silenced under laboratory conditions. However, their dissemination results in multidrug resistance in different clinical pathogens. In this study, we have identified an efflux pump from Streptomyces coelicolor, SCO4121, belonging to the MFS family of transporters and characterized its role in antibiotic resistance. SCO4121, provided resistance to multiple dissimilar drugs upon overexpression into both native and heterologous hosts. Further, deletion of SCO4121 resulted in increased sensitivity towards ciprofloxacin and chloramphenicol, suggesting the pump to be a major transporter of these substrates. Apart from providing multidrug resistance, SCO4121 imparted increased tolerance against the strong oxidant HOCl. In the wild type Streptomyces coelicolor cells, these drugs were found to transcriptionally regulate the pump in a concentration-dependent manner. Additionally, we identified SCO4122, a MarR regulator that positively regulates SCO4121 in response to the various drugs and oxidant HOCl. Thus, through these studies we present the multiple roles of SCO4121 in S. coelicolor and highlight the intricate mechanisms via which it is regulated in response to antibiotics and oxidative stress. IMPORTANCE One of the key mechanisms of drug resistance in bacteria is overexpression of efflux pumps. Streptomyces species are a reservoir of a large number of efflux pumps, potentially to provide resistance to both endogenous and non-endogenous antibiotics. While many of these pumps are not expressed under standard laboratory conditions, they result in resistance to multiple drugs when spread to other bacterial pathogens through horizontal gene transfer. In this study, we have identified a widely conserved, efflux pump, SCO4121 from Streptomyces coelicolor with roles in both multidrug resistance and oxidative stress tolerance. We also report the presence of an adjacently placed MarR regulator, SCO4122 which positively regulates SCO4121 in presence of diverse substrates in a redox-responsive manner. This study highlights that studying soil bacteria such as Streptomyces can reveal novel mechanisms of antibiotic resistance that may potentially emerge in clinically important bacteria.

A Fast Lasso-Based Method for Inferring Higher-Order Interactions

“…The second most common synonymous variant was another A to G change in PA3709 encoding Ala 340 of a probable major facilitator superfamily (MFS) transporter protein. Overexpression of efflux pumps that include MFS transporters are associated with increased resistance to antibiotics [15, 40].…”

“…The second most common synonymous variant was another A to G change in PA3709 encoding Ala 340 of a probable major facilitator superfamily (MFS) transporter protein. Overexpression of efflux pumps that include MFS transporters are associated with increased resistance to antibiotics [14,39]. Despite none of the pairwise effects having known interactions, the majority variants identified are very poorly characterised so the possibility of a true combined effect of Ciprofloxacin resistance cannot be ruled out.…”

In vitro activities of licochalcone A against planktonic cells and biofilm of Enterococcus faecalis

“…Our results demonstrated that there were mutations in multiple transcriptional genes (MarR family transcriptional regulator, TetR family transcriptional regulator, and MerR family transcriptional regulator). At present, MarR family transcriptional regulator and TetR family transcriptional regulator were found that closely related to bacterial oxidative stress, biofilm formation, and drug resistance by regulating the efflux pump and signal transduction (Colclough et al, 2019;Fritsch et al, 2019;Nag and Mehra, 2021;Van Loi et al, 2021). Licochalcone A may have multiple target genes in E. faecalis, for instance, the MarR family transcriptional regulator and TetR family transcriptional regulator may be the target genes of licochalcone A in E. faecalis in this study, which lead to licochalcone A and has a high drug resistance barrier to E. faecalis.…”

Uncovering and Engineering a Mini-Regulatory Network of the TetR-Family Regulator SACE_0303 for Yield Improvement of Erythromycin in Saccharopolyspora erythraea

“…( Grove, 2013 ). In spite of abundant distribution of MFRs in the antibiotic-producing actinomycetes, just a few members have been characterized in Streptomyces ( Yang et al, 2010 ; Davis et al, 2013 ; Huang and Grove, 2013 ; Zhang et al, 2015 ; Guo et al, 2018 ; Kong et al, 2019 ; Nag and Mehra, 2021 ), and the functional probe into MFRs in Sac. erythraea has not been reported.…”