Table 2. IncC enhancement of KorB DNA-binding activity in vitro.

Purified His-KorB and its deletion derivatives used	Kappa of KorB (nM)	Kappb of KorB (nM) in the presence of IncC	Kappa/Kappb
Wild-type KorB	1125	385	2.9
NΔ30	313	60	5.2
NΔ60	167	34	4.9
NΔ90	650	160	4.1
NΔ150	135	27	5.0
NΔ173	No binding	No binding	ND
BΔ11up	61	13	4.7
BΔ37up	520	346	1.5
BΔ10down	64	20	3.2
BΔ20down	29	16	1.8

^aK_app was estimated experimentally in EMSA as the concentration of purified His-tagged KorB derivatives needed to shift 50% of the radioactive fragment containing O_B. K_app for NΔ173 could not be experimentally established, no binding to DNA was observed at 10 µM.

^bK_app was estimated experimentally as the concentration of products of korB alleles needed to shift 50% of the labelled fragment in the presence of 581 nM IncC.