Article of Significant Interest Selected from This Issue by the Editors

A New Player in the Regulatory Pathway Controlling the Spread of Antibiotic Resistance in Cholera

Integrative and conjugative elements of the SXT/R391 family are the main drivers of the antibiotic resistance gene flow in the seventh pandemic lineage of Vibrio cholerae, the causative agent of cholera. Poulin-Laprade and Burrus (p. 3822–3833) have discovered a small transcriptional repressor, CroS, crucial for the stimulation of conjugative transfer of SXT/R391 elements in response to DNA damage. An SXT ΔcroS mutant is completely unresponsive to mitomycin C and exhibits increased expression of the master repressor SetR. The results suggest that the CroS and SetR regulatory circuit operates as a bistable switch similar to the DNA damage-sensing system Cro-CI of bacteriophage λ.