A Thermosensitive, Phase-Variable Epigenetic Switch: Revisited.

It has been more than a decade since the last comprehensive review of the phase-variable uropathogen-associated pyelonephritis-associated pilus () genetic switch. Since then, important data have come to light, including additional factors that regulate expression, better characterization of H-NS regulation, the structure of the Lrp octamer in complex with regulatory DNA, the temperature-insensitive phenotype of a mutant lacking the acetyltransferase RimJ, evidence that key components of the regulatory machinery are acetylated, and new insights into the role of DNA binding by key regulators in shaping both the physical structure and regulatory state of the and promoters. This review revisits , integrating these newer observations with older ones to produce a new model for the concerted behavior of this virulence-regulatory region.