Two ABC transporter operons and the antimicrobial resistance gene mtrF are pilT responsive in Neisseria gonorrhoeae

Abstract

Retraction of type IV pili is mediated by PilT. We show that loss of pilT function leads to upregulation of mtrF (multiple transferable resistance) and two operons encoding putative ABC transporters in Neisseria gonorrhoeae MS11. This effect occurs indirectly through the transcriptional regulator FarR, which until now has been shown to regulate only farAB. L-Glutamine can reverse pilT downregulation of the ABC transporter operons and mtrF.

FIG. 1.

Expression of putative ABC transporter genes (NGO0372, NGO2011, and NGO2014), mtrF, and farR in strain MS11ΔpilT 4 h postinfection. Transcript levels were measured by real-time quantitative RT-PCR. Each column represents the relative change of transcript level of the indicated gene in MS11ΔpilT compared to the level in wt MS11. Values and standard deviation are calculated from the results of four independent experiments.

FIG. 2.

Expression of putative ABC transporter genes (NGO0372 and NGO2011) and mtrF in the pilT mutant, the MS11ΔpilT strain, and the pilE mutant, MS11-307. Transcript levels were measured by real-time quantitative RT-PCR. Each column represents the relative change of transcript level of the indicated gene in the mutant background compared to the level in wt MS11. Values and standard deviation are calculated from the results of four independent experiments.

FIG. 3.

Expression of mtrF and putative ABC transporter genes (NGO0372 and NGO2011) in the MS11 ΔpilT and MS11 farR strains. Transcript levels are measured by real-time quantitative RT-PCR 4 h postinfection. Each column represents the relative change of transcript level of the indicated gene in the mutant background compared to the level in wt MS11. Values and standard deviation are calculated from the results of three independent experiments.