Mechanism of Resistance in Neisseria gonorrhoeae to Innate Human Antimicrobials
In the absence of cytotoxic inducers, MtrR represses the mtrCDE multidrug efflux system in Neisseria gonorrhoeae. “Mutated” MtrR is associated with multidrug-resistant clinical isolates. Beggs et al. (e00401-19) report an induced structure of MtrR, leading to the identification of two bile salts, which act as innate antimicrobials at gonococcal infection sites, as physiologically relevant inducers. MtrR-bile salt binding and their ability to derepress the mtrC promoter are characterized. Residues R176 and W136 are shown to be critical for binding one of these inducers. This study provides molecular insight into the ability of N. gonorrhoeae to combat innate human defenses.
The Role of σ Factors in Class II pilE Expression in Neisseria meningitidis
Neisseria meningitidis expresses one of two distinct classes of type four pilus (Tfp)—class I or class II—which can be distinguished by the locus encoding the major subunit, PilE. Lobanovska et al. (e00170-19) show that the class II pilE promoter harbors conserved σN and σ70 binding sites; however, transcription initiates only from the σ70-dependent promoter, even under different stress conditions. By deletion or overexpression of sigma factors, they show that σN, σH, and σE do not affect class II pilin expression, consistent with a role of the housekeeping σD in expression of this important component of Tfp.
- Copyright © 2019 American Society for Microbiology.
