Figure 3.

MATE45^long has metabolite efflux activity. (a) Mutant Escherichia coli strain acrB that is defective in the AcrAB‐TolC efflux system was transformed with ORFs MATE45 ^long, MATE45 ^med, MATE45 ^short or yellow florescent protein (Control), and grown in the presence or absence of 1 mM of the toxin tetrabultylammonium (TBA). Bacterial growth absorbance is indicated on the vertical axis and time after initiating the culture is indicated on the horizontal axis. In the absence of toxin, all genotypes reached exponential growth at the same time, ensuring that equal numbers of bacteria were plated for each genotype. Only the MATE45 ^long ORF provided tolerance to TBA toxin, as demonstrated by the failure to delay exponential growth. (b) acrB transformed with the MATE45 ^long ORF or yellow florescent protein (Control) was grown in the presence or absence of different concentrations of the toxin TBA. MATE45 ^long provided tolerance to the toxin, as demonstrated by earlier times until exponential phase growth in the present of the toxin. (c) mate45‐1^long lacked MATE efflux activity. acrB was transformed with the ORF mate45‐1 ^long, MATE45 ^long, or yellow florescent protein (Control) and grown in the presence or absence of 1 mM TBA toxin. mate45‐1 ^long failed to provide tolerance to the TBA, as demonstrated by similar growth curve compared to the control