A bistable prokaryotic differentiation system underlying development of conjugative transfer competence
Fig 1
ICEclc life-style and transfer competence development.
A Chromosomally-integrated ICE (black bar, schematically) activates and excises in rare transfer competent cells (tc, black circle; cell highlighted in orange), and transfers by conjugation to a new recipient (here in blue shading), where it inserts site-specifically and maintains through chromosomal replication. B Integrated ICEclc is delineated between the two attachment (att) sites (vertical lines). Layout shows the location of the core region relative to the integrase gene, the variable gene region with the clc genes for chlorocatechol and amn for 2-aminophenol metabolism, and the key regulator genes mfsR-tciR. Gene map below shows individual core genes (black and colored arrows, relevant gene names underneath), previously Northern-mapped transcripts and their orientation (in brown), fragments tested for promoter studies (letters on top) and hooked arrows pointing to identified promoters (P58432 being inconclusive). Asterisks point to those promoters being expressed in tc cell subpopulations. Regions indicated with a Δ denote deletions for transfer studies. C General strategy of single copy chromosomally delivered individual or paired promoter-fluorescent gene reporter fusions using mini-transposon delivery.