Dual role of the carboxyl-terminal region of pig liver L-kynurenine 3-monooxygenase: mitochondrial-targeting signal and enzymatic activity
| Autor: | Kuniaki Saito, Tomihiko Uemura, Seiich Haga, Kumiko Hirai, Susumu Izumi, Hidehito Kuroyanagi, Yoshitaka Tatebayashi, Yoshitaka Hayashi, Kanako Hirabayashi-Takahashi |
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| Rok vydání: | 2010 |
| Předmět: |
Arginine
Swine Molecular Sequence Data Mitochondria Liver Flavin group Mitochondrion Biology Biochemistry Mitochondrial Proteins Hydroxylation chemistry.chemical_compound Kynurenine 3-Monooxygenase Chlorocebus aethiops Animals Humans Amino Acid Sequence Cloning Molecular Molecular Biology Kynurenine Sequence Deletion Intracellular Signaling Peptides and Proteins General Medicine Monooxygenase Recombinant Proteins Protein Structure Tertiary Enzyme Activation chemistry COS Cells Mitochondrial Membranes Biocatalysis Monoamine oxidase B Peptides Bacterial outer membrane Oligopeptides Sequence Alignment Sequence Analysis NADP |
| Zdroj: | Journal of Biochemistry. 148:639-650 |
| ISSN: | 0021-924X |
| DOI: | 10.1093/jb/mvq099 |
| Popis: | L-kynurenine 3-monooxygenase (KMO) is an NAD(P)H-dependent flavin monooxygenase that catalyses the hydroxylation of L -kynurenine to 3-hydroxykynurenine, and is localized as an oligomer in the mitochondrial outer membrane. In the human brain, KMO may play an important role in the formation of two neurotoxins, 3-hydroxykynurenine and quinolinic acid, both of which provoke severe neurodegenerative diseases. In mosquitos, it plays a role in the formation both of eye pigment and of an exflagellation-inducing factor (xanthurenic acid). Here, we present evidence that the C-terminal region of pig liver KMO plays a dual role. First, it is required for the enzymatic activity. Second, it functions as a mitochondrial targeting signal as seen in monoamine oxidase B (MAO B) or outer membrane cytochrome b 5 . The first role was shown by the comparison of the enzymatic activity of two mutants (C-terminally FLAG-tagged KMO and carboxyl-terminal truncation form, KMOΔC50) with that of the wild-type enzyme expressed in COS-7 cells. The second role was demonstrated with fluorescence microscopy by the comparison of the intracellular localization of the wild-type, three carboxyl-terminal truncated forms (AC20, AC30 and ΔC50), C-terminally FLAG-tagged wild-type and a mutant KMO, where two arginine residues, Arg461-Arg462, were replaced with Ser residues. |
| Databáze: | OpenAIRE |
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