| Structural highlights
Function
[AAUA_ALCFA] Oxidizes primary aromatic amines and, more slowly, some long-chain aliphatic amines, but not methylamine or ethylamine. Uses azurin as an electron acceptor to transfer electrons from the reduced tryptophylquinone cofactor.[1] [2] [3] [4] [5] [6] [7] [AAUB_ALCFA] Oxidizes primary aromatic amines and, more slowly, some long-chain aliphatic amines, but not methylamine or ethylamine. Uses azurin as an electron acceptor to transfer electrons from the reduced tryptophylquinone cofactor.[8] [9] [10] [11]
Evolutionary Conservation
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Publication Abstract from PubMed
The quinoprotein aromatic amine dehydrogenase (AADH) uses a covalently bound tryptophan tryptophylquinone (TTQ) cofactor to oxidatively deaminate primary aromatic amines. Recent crystal structures have provided insight into the reductive half-reaction. In contrast, no atomic details are available for the oxidative half-reaction. The TTQ O7 hydroxyl group is protonated during reduction, but it is unclear how this proton can be removed during the oxidative half-reaction. Furthermore, compared with the electron transfer from the N-quinol form, electron transfer from the non-physiological O-quinol form to azurin is significantly slower. Here we report crystal structures of the O-quinol, N-quinol, and N-semiquinone forms of AADH. A comparison of oxidized and substrate reduced AADH species reveals changes in the TTQ-containing subunit, extending from residues in the immediate vicinity of the N-quinol to the putative azurin docking site, suggesting a mechanism whereby TTQ redox state influences interprotein electron transfer. In contrast, chemical reduction of the TTQ center has no significant effect on protein conformation. Furthermore, structural reorganization upon substrate reduction places a water molecule near TTQ O7 where it can act as proton acceptor. The structure of the N-semiquinone, however, is essentially similar to oxidized AADH. Surprisingly, in the presence of substrate a covalent N-semiquinone substrate adduct is observed. To our knowledge this is the first detailed insight into a complex, branching mechanism of quinone oxidation where significant structural reorganization upon reduction of the quinone center directly influences formation of the electron transfer complex and nature of the electron transfer process.
Atomic level insight into the oxidative half-reaction of aromatic amine dehydrogenase.,Roujeinikova A, Scrutton NS, Leys D J Biol Chem. 2006 Dec 29;281(52):40264-72. Epub 2006 Sep 27. PMID:17005560[12]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Chistoserdov AY. Cloning, sequencing and mutagenesis of the genes for aromatic amine dehydrogenase from Alcaligenes faecalis and evolution of amine dehydrogenases. Microbiology. 2001 Aug;147(Pt 8):2195-202. PMID:11495996
- ↑ Hothi P, Khadra KA, Combe JP, Leys D, Scrutton NS. Tryptophan tryptophylquinone cofactor biogenesis in the aromatic amine dehydrogenase of Alcaligenes faecalis. Cofactor assembly and catalytic properties of recombinant enzyme expressed in Paracoccus denitrificans. FEBS J. 2005 Nov;272(22):5894-909. PMID:16279953 doi:http://dx.doi.org/EJB4990
- ↑ Govindaraj S, Eisenstein E, Jones LH, Sanders-Loehr J, Chistoserdov AY, Davidson VL, Edwards SL. Aromatic amine dehydrogenase, a second tryptophan tryptophylquinone enzyme. J Bacteriol. 1994 May;176(10):2922-9. PMID:8188594
- ↑ Edwards SL, Davidson VL, Hyun YL, Wingfield PT. Spectroscopic evidence for a common electron transfer pathway for two tryptophan tryptophylquinone enzymes. J Biol Chem. 1995 Mar 3;270(9):4293-8. PMID:7876189
- ↑ Sukumar N, Chen ZW, Ferrari D, Merli A, Rossi GL, Bellamy HD, Chistoserdov A, Davidson VL, Mathews FS. Crystal structure of an electron transfer complex between aromatic amine dehydrogenase and azurin from Alcaligenes faecalis. Biochemistry. 2006 Nov 14;45(45):13500-10. PMID:17087503 doi:http://dx.doi.org/10.1021/bi0612972
- ↑ Roujeinikova A, Scrutton NS, Leys D. Atomic level insight into the oxidative half-reaction of aromatic amine dehydrogenase. J Biol Chem. 2006 Dec 29;281(52):40264-72. Epub 2006 Sep 27. PMID:17005560 doi:http://dx.doi.org/10.1074/jbc.M605559200
- ↑ Masgrau L, Roujeinikova A, Johannissen LO, Hothi P, Basran J, Ranaghan KE, Mulholland AJ, Sutcliffe MJ, Scrutton NS, Leys D. Atomic description of an enzyme reaction dominated by proton tunneling. Science. 2006 Apr 14;312(5771):237-41. PMID:16614214 doi:312/5771/237
- ↑ Chistoserdov AY. Cloning, sequencing and mutagenesis of the genes for aromatic amine dehydrogenase from Alcaligenes faecalis and evolution of amine dehydrogenases. Microbiology. 2001 Aug;147(Pt 8):2195-202. PMID:11495996
- ↑ Hothi P, Khadra KA, Combe JP, Leys D, Scrutton NS. Tryptophan tryptophylquinone cofactor biogenesis in the aromatic amine dehydrogenase of Alcaligenes faecalis. Cofactor assembly and catalytic properties of recombinant enzyme expressed in Paracoccus denitrificans. FEBS J. 2005 Nov;272(22):5894-909. PMID:16279953 doi:http://dx.doi.org/EJB4990
- ↑ Govindaraj S, Eisenstein E, Jones LH, Sanders-Loehr J, Chistoserdov AY, Davidson VL, Edwards SL. Aromatic amine dehydrogenase, a second tryptophan tryptophylquinone enzyme. J Bacteriol. 1994 May;176(10):2922-9. PMID:8188594
- ↑ Masgrau L, Roujeinikova A, Johannissen LO, Hothi P, Basran J, Ranaghan KE, Mulholland AJ, Sutcliffe MJ, Scrutton NS, Leys D. Atomic description of an enzyme reaction dominated by proton tunneling. Science. 2006 Apr 14;312(5771):237-41. PMID:16614214 doi:312/5771/237
- ↑ Roujeinikova A, Scrutton NS, Leys D. Atomic level insight into the oxidative half-reaction of aromatic amine dehydrogenase. J Biol Chem. 2006 Dec 29;281(52):40264-72. Epub 2006 Sep 27. PMID:17005560 doi:http://dx.doi.org/10.1074/jbc.M605559200
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