| Structural highlights
5cku is a 1 chain structure with sequence from Aspfu. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
| | Ligands: | , , , , |
| Gene: | sidA, Afu2g07680 (ASPFU) |
| Activity: | L-ornithine N(5)-monooxygenase (NAD(P)H), with EC number 1.14.13.196 |
| Resources: | FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT |
Function
[SIDA_ASPFU] Catalyzes the conversion of L-ornithine to N(5)-hydroxyornithine, the first step in the biosynthesis of all hydroxamate-containing siderophores, such as the secreted triacetylfusarinine C (TAFC) involved in iron uptake and the intracellular iron storage compound desferriferricrocin (DFFC). Highly specific for its substrate, only hydrolyzing l-ornithine. Has preference for NADPH over NADH, NADPH playing a role in stabilization of the C4a-hydroperoxyflavin intermediate. Essential for virulence.[1] [2] [3] [4]
Publication Abstract from PubMed
The SidA ornithine N5-monooxygenase from Aspergillusfumigatus is a flavin monooxygenase that catalyzes the NADPH-dependent hydroxylation of ornithine. Herein we report a mutagenesis study targeting four residues that contact ornithine in crystal structures of SidA: Lys107, Asn293, Asn323, and Ser469. Mutation of Lys107 to Ala abolishes activity as measured in steady-state oxygen consumption and ornithine hydroxylation assays, indicating that the ionic interaction of Lys107 with the carboxylate of ornithine is essential for catalysis. Mutation of Asn293, Asn323, or Ser469 individually to Ala results in >14-fold increases in Km values for ornithine. Asn323 to Ala also increases the rate constant for flavin reduction by NADPH by 18-fold. Asn323 is unique among the four ornithine binding residues in that it also interacts with NADPH by forming a hydrogen bond with the nicotinamide ribose. The crystal structure of N323A complexed with NADP+ and ornithine shows that the nicontinamide riboside group of NADP is disordered. This result suggests that the increase in flavin reduction rate results from an increase in conformational space available to the enzyme-bound NADP(H). Asn323 thus facilitates ornithine binding at the expense of hindering flavin reduction, which demonstrates the delicate balance that exists within protein-ligand interaction networks in enzyme active sites.
Contribution to catalysis of ornithine binding residues in ornithine N5-monooxygenase.,Robinson R, Qureshi IA, Klancher CA, Rodriguez PJ, Tanner JJ, Sobrado P Arch Biochem Biophys. 2015 Sep 12;585:25-31. doi: 10.1016/j.abb.2015.09.008. PMID:26375201[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Schrettl M, Bignell E, Kragl C, Joechl C, Rogers T, Arst HN Jr, Haynes K, Haas H. Siderophore biosynthesis but not reductive iron assimilation is essential for Aspergillus fumigatus virulence. J Exp Med. 2004 Nov 1;200(9):1213-9. Epub 2004 Oct 25. PMID:15504822 doi:http://dx.doi.org/jem.20041242
- ↑ Hissen AH, Wan AN, Warwas ML, Pinto LJ, Moore MM. The Aspergillus fumigatus siderophore biosynthetic gene sidA, encoding L-ornithine N5-oxygenase, is required for virulence. Infect Immun. 2005 Sep;73(9):5493-503. PMID:16113265 doi:http://dx.doi.org/10.1128/IAI.73.9.5493-5503.2005
- ↑ Chocklett SW, Sobrado P. Aspergillus fumigatus SidA is a highly specific ornithine hydroxylase with bound flavin cofactor. Biochemistry. 2010 Aug 10;49(31):6777-83. doi: 10.1021/bi100291n. PMID:20614882 doi:http://dx.doi.org/10.1021/bi100291n
- ↑ Romero E, Fedkenheuer M, Chocklett SW, Qi J, Oppenheimer M, Sobrado P. Dual role of NADP(H) in the reaction of a flavin dependent N-hydroxylating monooxygenase. Biochim Biophys Acta. 2012 Jun;1824(6):850-7. doi: 10.1016/j.bbapap.2012.03.004. , Epub 2012 Mar 27. PMID:22465572 doi:http://dx.doi.org/10.1016/j.bbapap.2012.03.004
- ↑ Robinson R, Qureshi IA, Klancher CA, Rodriguez PJ, Tanner JJ, Sobrado P. Contribution to catalysis of ornithine binding residues in ornithine N5-monooxygenase. Arch Biochem Biophys. 2015 Sep 12;585:25-31. doi: 10.1016/j.abb.2015.09.008. PMID:26375201 doi:http://dx.doi.org/10.1016/j.abb.2015.09.008
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