7US3

Structure of Putrescine N-hydroxylase Involved Complexed with NADP+

Summary for 7US3

• Entry DOI: 10.2210/pdb7us3/pdb
• Descriptor: Putrescine N-hydroxylase, FLAVIN-ADENINE DINUCLEOTIDE, NADP NICOTINAMIDE-ADENINE-DINUCLEOTIDE PHOSPHATE, ... (6 entities in total)
• Functional Keywords: monooxygenase, putrescine n-hydroxylase, flavoprotein
• Biological source: Acinetobacter baumannii
• Total number of polymer chains: 4
• Total formula weight: 220844.13

Authors

Tanner, J.J.,Bogner, A.N. (deposition date: 2022-04-22, release date: 2022-11-30, Last modification date: 2023-10-25)

Primary citation

Lyons, N.S.,Bogner, A.N.,Tanner, J.J.,Sobrado, P.
Kinetic and Structural Characterization of a Flavin-Dependent Putrescine N -Hydroxylase from Acinetobacter baumannii.
Biochemistry, 61:2607-2620, 2022

PubMed Abstract: is a Gram-negative opportunistic pathogen that causes nosocomial infections, especially among immunocompromised individuals. The rise of multidrug resistant strains of has limited the use of standard antibiotics, highlighting a need for new drugs that exploit novel mechanisms of pathogenicity. Disrupting iron acquisition by inhibiting the biosynthesis of iron-chelating molecules (siderophores) secreted by the pathogen is a potential strategy for developing new antibiotics. Here we investigated FbsI, an -hydroxylating monooxygenase involved in the biosynthesis of fimsbactin A, the major siderophore produced by FbsI was characterized using steady-state and transient-state kinetics, spectroscopy, X-ray crystallography, and small-angle X-ray scattering. FbsI was found to catalyze the -hydroxylation of the aliphatic diamines putrescine and cadaverine. Maximum coupling of the reductive and oxidative half-reactions occurs with putrescine, suggesting it is the preferred () substrate. FbsI uses both NADPH and NADH as the reducing cofactor with a slight preference for NADPH. The crystal structure of FbsI complexed with NADP was determined at 2.2 Å resolution. The structure exhibits the protein fold characteristic of Class B flavin-dependent monooxygenases. FbsI is most similar in 3D structure to the cadaverine -hydroxylases DesB and DfoA. Small-angle X-ray scattering shows that FbsI forms a tetramer in solution like the -hydroxylating monooxygenases of the SidA/IucD/PvdA family. A model of putrescine docked into the active site provides insight into substrate recognition. A mechanism for the catalytic cycle is proposed where dehydration of the C4a-hydroxyflavin intermediate is partially rate-limiting, and the hydroxylated putrescine product is released before NADP.

PubMed: 36314559
DOI: 10.1021/acs.biochem.2c00493

Experimental method

X-RAY DIFFRACTION (2.2 Å)