Biology:NDUFB9
 Generic protein structure example |
NADH dehydrogenase [ubiquinone] 1 beta subcomplex subunit 9 is an enzyme that in humans is encoded by the NDUFB9 gene.[1][2] NADH dehydrogenase (ubiquinone) 1 beta subcomplex subunit 9 is an accessory subunit of the NADH dehydrogenase (ubiquinone) complex, located in the mitochondrial inner membrane. It is also known as Complex I and is the largest of the five complexes of the electron transport chain.[3]
Structure
The NDUFB9 gene is located on the q arm of chromosome 8 in position 13.3 and is 10,884 base pairs long. The NDUFB9 protein weighs 22 kDa and is composed of 179 amino acids.[4][5] NDUFB9 is a subunit of the enzyme NADH dehydrogenase (ubiquinone), the largest of the respiratory complexes. The structure is L-shaped with a long, hydrophobic transmembrane domain and a hydrophilic domain for the peripheral arm that includes all the known redox centers and the NADH binding site.[3] It has been noted that the N-terminal hydrophobic domain has the potential to be folded into an alpha helix spanning the inner mitochondrial membrane with a C-terminal hydrophilic domain interacting with globular subunits of Complex I. The highly conserved two-domain structure suggests that this feature is critical for the protein function and that the hydrophobic domain acts as an anchor for the NADH dehydrogenase (ubiquinone) complex at the inner mitochondrial membrane.[2]
Function
The protein encoded by this gene is an accessory subunit of the multisubunit NADH:ubiquinone oxidoreductase (complex I) that is not directly involved in catalysis. Mammalian complex I is composed of 45 different subunits. It locates at the mitochondrial inner membrane. This protein complex has NADH dehydrogenase activity and oxidoreductase activity. It transfers electrons from NADH to the respiratory chain. The immediate electron acceptor for the enzyme is believed to be ubiquinone. Alternative splicing occurs at this locus and two transcript variants encoding distinct isoforms have been identified.[2] Initially, NADH binds to Complex I and transfers two electrons to the isoalloxazine ring of the flavin mononucleotide (FMN) prosthetic arm to form FMNH2. The electrons are transferred through a series of iron-sulfur (Fe-S) clusters in the prosthetic arm and finally to coenzyme Q10 (CoQ), which is reduced to ubiquinol (CoQH2). The flow of electrons changes the redox state of the protein, resulting in a conformational change and pK shift of the ionizable side chain, which pumps four hydrogen ions out of the mitochondrial matrix.[3]
Clinical significance
A mutation in NDUFB9 resulting in reduction in NDUFB9 protein and both amount and activity of complex I has been shown to be a causal mutation leading to Complex I deficiency.[6]
References
- ↑ "The human B22 subunit of the NADH-ubiquinone oxidoreductase maps to the region of chromosome 8 involved in branchio-oto-renal syndrome". Genomics 35 (1): 6–10. Sep 1996. doi:10.1006/geno.1996.0316. PMID 8661098.
- ↑ 2.0 2.1 2.2 "Entrez Gene: NDUFB9 NADH dehydrogenase (ubiquinone) 1 beta subcomplex, 9, 22kDa". https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=4715.
- ↑ 3.0 3.1 3.2 Voet, Donald; Voet, Judith G.; Pratt, Charlotte W. (2013). "Chapter 18". Fundamentals of biochemistry: life at the molecular level (4th ed.). Hoboken, NJ: Wiley. pp. 581–620. ISBN 978-0-470-54784-7.
- ↑ "Integration of cardiac proteome biology and medicine by a specialized knowledgebase". Circulation Research 113 (9): 1043–53. Oct 2013. doi:10.1161/CIRCRESAHA.113.301151. PMID 23965338.
- ↑ "NADH dehydrogenase [ubiquinone 1 beta subcomplex subunit 9"]. Cardiac Organellar Protein Atlas Knowledgebase (COPaKB). https://amino.heartproteome.org/web/protein/Q9Y6M9.
- ↑ Haack, TB; Madignier, F; Herzer, M; Lamantea, E; Danhauser, K; Invernizzi, F; Koch, J; Freitag, M et al. (February 2012). "Mutation screening of 75 candidate genes in 152 complex I deficiency cases identifies pathogenic variants in 16 genes including NDUFB9.". Journal of Medical Genetics 49 (2): 83–9. doi:10.1136/jmedgenet-2011-100577. PMID 22200994.
Further reading
- "Intron based radiation hybrid mapping of 15 complex I genes of the human electron transport chain.". Cytogenet. Cell Genet. 82 (1–2): 115–9. 1998. doi:10.1159/000015082. PMID 9763677.
- "cDNA of eight nuclear encoded subunits of NADH:ubiquinone oxidoreductase: human complex I cDNA characterization completed.". Biochem. Biophys. Res. Commun. 253 (2): 415–22. 1999. doi:10.1006/bbrc.1998.9786. PMID 9878551.
- "Human NDUFB9 gene: genomic organization and a possible candidate gene associated with deafness disorder mapped to chromosome 8q13.". Hum. Hered. 49 (2): 75–80. 1999. doi:10.1159/000022848. PMID 10077726.
- "Shotgun sequencing of the human transcriptome with ORF expressed sequence tags.". Proc. Natl. Acad. Sci. U.S.A. 97 (7): 3491–6. 2000. doi:10.1073/pnas.97.7.3491. PMID 10737800. Bibcode: 2000PNAS...97.3491D.
- "cDNA cloning by amplification of circularized first strand cDNAs reveals non-IRE-regulated iron-responsive mRNAs.". Biochem. Biophys. Res. Commun. 275 (1): 223–7. 2000. doi:10.1006/bbrc.2000.3282. PMID 10944468.
- "Cloning and functional analysis of cDNAs with open reading frames for 300 previously undefined genes expressed in CD34+ hematopoietic stem/progenitor cells.". Genome Res. 10 (10): 1546–60. 2001. doi:10.1101/gr.140200. PMID 11042152.
- "Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences.". Proc. Natl. Acad. Sci. U.S.A. 99 (26): 16899–903. 2003. doi:10.1073/pnas.242603899. PMID 12477932. Bibcode: 2002PNAS...9916899M.
- "The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC).". Genome Res. 14 (10B): 2121–7. 2004. doi:10.1101/gr.2596504. PMID 15489334.
- "A human protein-protein interaction network: a resource for annotating the proteome.". Cell 122 (6): 957–68. 2005. doi:10.1016/j.cell.2005.08.029. PMID 16169070. http://edoc.mpg.de/get.epl?fid=21592&did=275687&ver=0.
- "Towards a proteome-scale map of the human protein-protein interaction network.". Nature 437 (7062): 1173–8. 2005. doi:10.1038/nature04209. PMID 16189514. Bibcode: 2005Natur.437.1173R.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.
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