DNA manipulations were performed as in (Sambrook et al., 1989 ). E. coli S17-1λpir was used for cloning. iProof DNA polymerase (Bio-Rad) was used for regular PCR reactions, and PfuUltra DNA polymerase (Agilent) was used for constructing point mutations. Restriction enzymes, T4 polynucleotide kinase, Antarctic phosphatase, and T4 DNA ligase were purchased from New England Biolabs (NEB). Plasmids used in this study are described in Table S2. Primers from Integrated DNA Technologies (IDT) are listed in Table S3. All plasmids were confirmed by sequencing at Genewiz. Arabinose inducible qrr4, anhydrotetracycline inducible qrr4, and target-GFP translational fusions were constructed as described (Shao et al., 2013 (link)). V. cholerae mutants were constructed as described (Skorupski and Taylor, 1996 (link)).