Mammalian steroid hormones are substrates for the major RND- and MFS-type tripartite multidrug efflux pumps of Escherichia coli.
A steroid-hormone-dependent growth suppression was observed in Escherichia coli efflux-deficient backgrounds containing mutations in the major RND- and MFS-type tripartite multidrug efflux systems, AcrAB-TolC and EmrAB-TolC, respectively. In addition to their previously known natural steroid spectrum, which includes bile acids, both systems were shown to transport the hormones estradiol and progesterone, whereas hydrocortisone served as a substrate of only AcrAB-TolC. Furthermore, at least two other RND-type pumps, YhiV and AcrD, were capable of transporting such hormones when overexpressed on plasmid vectors (with some demonstrable specificity observed with AcrD). When this activity was examined in a wild-type background, cell-associated estradiol levels remained largely unaffected by competition with exogenous bile acids and hydrocortisone, in contrast to progesterone, which produced a significant modulation in estradiol uptake.
Elkins
Christopher A
CA
Division of Microbiology, National Center for Toxicological Research, 3900 NCTR Drive, Jefferson, AR 72079-9502, USA. chris.elkins@fda.hhs.gov
Mullis
Lisa B
LB
D001692:Biological Transport; D018432:Drug Resistance, Multiple; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D018892:Proton-Motive Force; D013256:Steroids / Q000378:metabolism*
D026901:Membrane Transport Proteins; D013256:Steroids