Figure 1.

Genome map of RK2 plasmid. a) RK2 whole genome map, 60,099 bp; KorA, KorB, TrbA, KorC are global regulators. Arrows to the promoters and signs indicate the binding sites of the regulators and a type of regulation (- is repression), oriV and oriT are origins of vegetative replication and transfer, respectively, blac - Tn1 (transportable element), grey - Tra1 and Tra2 (transfer genes), blue - partitioning function, red - the central control operon. b) The central control operon, consisting of korA, incC2/C1, korB, korG/F genes, is regulated by a single promoter (p) and ends at a terminator (t). The operon is negatively and co-operatively auto-regulated by KorA and KorB. c) Binding sites of KorA and KorB on the korAp promoter: KorB binds 40 bp upstream of the transcription start point (tsp), and KorA binds 33 bp downstream from KorB binding site (O_B1). KorA binds in -10 region, where RNAP binds.