@entity526 possesses a two-domain flavohemoglobin, Hmp, implicated in @entity842 (NO) detoxification. To determine the contribution of each domain of Hmp toward NO detoxification, we genetically engineered the Hmp protein and separately expressed the @entity1446 ( @entity2033 ) and the @entity1785 ( @entity10751 ) domains in a defined hmp mutant. Expression of each domain was confirmed by Western blot analysis. CO-difference spectra showed that the @entity2033 of Hmp can bind CO, but the CO adduct showed a slightly blue-shifted peak. Overexpression of the @entity2033 resulted in an improvement of growth to a similar extent to that observed with the Vitreoscilla hemeonly globin Vgb, whereas the @entity10751 alone did not improve growth. Viability of the hmp mutant in the presence of lethal concentrations of @entity1854 was increased (to 30% survival after 2 h in 5 mM @entity1854 ) by overexpressing Vgb or the @entity2033 . However, maximal protection was provided only by holo-Hmp (75% survival under the same conditions). Cellular respiration of the hmp mutant was instantaneously inhibited in the presence of 13.5 microM NO but remained insensitive to NO inhibition when these cells overexpressed Hmp. When @entity2033 or @entity10751 was expressed separately, no significant protection was observed. By contrast, overexpression of Vgb provided partial protection from NO respiratory inhibition. Our results suggest that, despite the homology between the @entity2033 from Hmp and Vgb (45% identity), their roles seem to be quite distinct.

Flavohemoglobin Hmp, but not its individual domains, confers protection from respiratory inhibition by XXXX in @entity526 .

@entity1785 :: ('MESH:C024132', 'Chemical') :: ['flavin'] @entity10751 :: ('MESH:D004402', 'Disease') :: ['FD'] @entity1854 :: ('MESH:D009599', 'Chemical') :: ['sodium nitroprusside'] @entity2033 :: ('MESH:D006816', 'Disease') :: ['HD'] @entity842 :: ('MESH:D009569', 'Chemical') :: ['nitric oxide'] @entity526 :: ('562', 'Species') :: ['Escherichia coli'] @entity1446 :: ('MESH:D006418', 'Chemical') :: ['heme']
@entity842 :: (MESH:D009569,Chemical) :: ['nitric oxide']
