Table 1.

Heme Translocation and ATP Hydrolysis for the Wild-Type and Mutant ShuUV Transporters^a

ShuUV transporter	total amount of heme transferred to ShuS (nmol)d	total amount of ATP hydrolysis (nmol)e
Wild-Type ShuUV System
ShuUVc	2.2 ± 0.1	1280 ± 40
ShuUV with ShuT	2.2 ± 0.1	1750 ± 44
ShuUV with heme-bound ShuTb	16 ± 0.7	4353 ± 328
ShuUV with heme-bound Glu-74 Val ShuTb	1.0 ± 0.04	2034 ± 153
ShuUV with heme-bound Glu-207 Val ShuTb	1.7 ± 0.1	1630 ± 33
ShuUV with heme-bound Glu-74/207 Val ShuTb	2.5 ± 0.35	1596 ± 43
ShuUV Mutant System
His-252 Alac	3.0 ± 0.1	1096 ± 68
His-252 Ala with heme-bound ShuTb	3.9 ± 0.42	1949 ± 78
His-262 Alac	2.0 ± 0.5	460 ± 35
His-262 Ala with heme-bound ShuTb	2.6 ± 0.15	580 ± 74
His-252/262 Alac	2.0 ± 0.5	952 ± 47
His-262 Ala with heme-bound ShuTb	2.6 ± 0.15	895 ± 238

^aThe amount of heme-bound ShuT within the lumen was calculated by pyridine hemochrome to be 17 ± 0.6 nmol.

^bThe amount of heme-bound ShuT within the lumen was calculated by pyridine hemochrome to be 17 ± 0.6 nmol.

^cBasal ATP hydrolysis measured in the absence of ShuT.

^dThe amount of heme transferred to ShuS at the 10 min time point was measured by pyridine hemochrome following removal of the liposomes.

^eTotal ATP hydrolysis at the 10 min time point.