Table 2.

TtpC2 is an essential component of the TtpC2-TonB2 system in mediating the uptake of endogenous siderophores in V. vulnificus

V. vulnificus strain or genotype	Growth on indicated iron sourcea
	FAC	Vulnibactin	Hydroxamate
WT	+	+	+
ΔtonB1	+	+	+
ΔtonB2	+	+	+
ΔttpC2	+	+	+
ΔtonB3	+	+	+
ΔtonB1 ΔtonB2	+	−	−
ΔtonB1 ΔttpC2	+	−	−
ΔtonB1 ΔtonB3	+	+	+
ΔtonB2 ΔtonB3	+	+	+
ΔtonB1 ΔtonB2 ΔtonB3	+	−	−
ΔtonB1 ΔttpC2 ΔttpC3/pMMB208	+	−	−
ΔtonB1 ΔttpC2 ΔttpC3/pttpC2(Vvul)	+	+	+

^aGrowth was determined by the presence of a halo (+) or lack thereof (−) around the iron source indicated. FAC, which does not require active transport, was added as a positive control to confirm that the strain imbedded within the plate was viable. Two microliters of FAC was spotted (500 μg/ml). Wild-type V. vulnificus was streaked onto the plate, and the halo of growth was monitored around the streak. A V. vulnificus ΔvenB mutant strain that is deficient in the production of vulnibactin was streaked onto the plate, and the halo of growth was monitored around the streak.