A cryptic transcription factor regulates Caulobacter adhesin development
Fig 1
Adhesion TCS pathway and adhesion profiling of lovKH180A::Tn mutants.
A) Schematic of the LovK-SpdSR-SkaH adhesion TCS system that regulates holdfast synthesis as described by Reyes-Ruiz et al. [16]. Question marks indicate postulated additional regulator(s) in the adhesion control pathway. Dashed lines indicate post-transcriptional regulation and solid lines indicate transcriptional regulation. Black arrows indicate activation and red bar-ended lines indicate repression. B) Genetic selection to identify insertions that disrupt the hyper-holdfast phenotype of lovKH180A. Tn-himar strains were cultivated and serially passaged for five days in the presence of cheesecloth (black cross-hatched lines in the center of the well). Mutants that do not permanently adhere to cheesecloth are increasingly enriched in the supernatant with each passage. Darker yellow color indicates non-adhesive lovKH180A::Tn strains that are enriched after five days of serial passaging. C) (left) List of the 25 genes for which transposon insertion has the largest disruptive effect on adhesion of the lovKH180A strain. (right) Enrichment in the supernatant is reflected in an increasing calculated fitness score with each daily passage. Mutations that disrupt lovKH180A adhesion to cheesecloth include the expected holdfast synthesis and modification genes (pink), and genes encoding the LovK-SpdSR-SkaH regulatory system (blue). The hypothetical gene CCNA_00551 is listed in black; all remaining genes are colored grey.