Download MendeleyStructural and Biochemical Characterization of the Flavin-Dependent Siderophore-Interacting Protein from Acinetobacter baumannii .
Valentino, H., Korasick, D.A., Bohac, T.J., Shapiro, J.A., Wencewicz, T.A., Tanner, J.J., Sobrado, P.(2021) ACS Omega 6: 18537-18547
- PubMed: 34308084
- DOI: https://doi.org/10.1021/acsomega.1c03047
- Primary Citation of Related Structures:
7LRN - PubMed Abstract:
Acinetobacter baumannii is an opportunistic pathogen with a high mortality rate due to multi-drug-resistant strains. The synthesis and uptake of the iron-chelating siderophores acinetobactin (Acb) and preacinetobactin (pre-Acb) have been shown to be essential for virulence. Here, we report the kinetic and structural characterization of BauF, a flavin-dependent siderophore-interacting protein (SIP) required for the reduction of Fe(III) bound to Acb/pre-Acb and release of Fe(II). Stopped-flow spectrophotometric studies of the reductive half-reaction show that BauF forms a stable neutral flavin semiquinone intermediate. Reduction with NAD(P)H is very slow ( k obs , 0.001 s -1 ) and commensurate with the rate of reduction by photobleaching, suggesting that NAD(P)H are not the physiological partners of BauF. The reduced BauF was oxidized by Acb-Fe ( k obs , 0.02 s -1 ) and oxazole pre-Acb-Fe (ox-pre-Acb-Fe) ( k obs , 0.08 s -1 ), a rigid analogue of pre-Acb, at a rate 3-11 times faster than that with molecular oxygen alone. The structure of FAD-bound BauF was solved at 2.85 Å and was found to share a similarity to Shewanella SIPs. The biochemical and structural data presented here validate the role of BauF in A. baumannii iron assimilation and provide information important for drug design.
Organizational Affiliation:
Department of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States.
