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The molecular features of uncoupling protein 1 support a conventional mitochondrial carrier-like mechanism

Uncoupling protein 1 (UCP1) is an integral membrane protein found in the mitochondrial inner membrane of brown adipose tissue, and facilitates the process of non-shivering thermogenesis in mammals. Its activation by fatty acids, which overcomes its inhibition by purine nucleotides, leads to an incre...

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Autores principales: Crichton, Paul G., Lee, Yang, Kunji, Edmund R.S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5395090/
https://www.ncbi.nlm.nih.gov/pubmed/28057583
http://dx.doi.org/10.1016/j.biochi.2016.12.016
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author Crichton, Paul G.
Lee, Yang
Kunji, Edmund R.S.
author_facet Crichton, Paul G.
Lee, Yang
Kunji, Edmund R.S.
author_sort Crichton, Paul G.
collection PubMed
description Uncoupling protein 1 (UCP1) is an integral membrane protein found in the mitochondrial inner membrane of brown adipose tissue, and facilitates the process of non-shivering thermogenesis in mammals. Its activation by fatty acids, which overcomes its inhibition by purine nucleotides, leads to an increase in the proton conductance of the inner mitochondrial membrane, short-circuiting the mitochondrion to produce heat rather than ATP. Despite 40 years of intense research, the underlying molecular mechanism of UCP1 is still under debate. The protein belongs to the mitochondrial carrier family of transporters, which have recently been shown to utilise a domain-based alternating-access mechanism, cycling between a cytoplasmic and matrix state to transport metabolites across the inner membrane. Here, we review the protein properties of UCP1 and compare them to those of mitochondrial carriers. UCP1 has the same structural fold as other mitochondrial carriers and, in contrast to past claims, is a monomer, binding one purine nucleotide and three cardiolipin molecules tightly. The protein has a single substrate binding site, which is similar to those of the dicarboxylate and oxoglutarate carriers, but also contains a proton binding site and several hydrophobic residues. As found in other mitochondrial carriers, UCP1 has two conserved salt bridge networks on either side of the central cavity, which regulate access to the substrate binding site in an alternating way. The conserved domain structures and mobile inter-domain interfaces are consistent with an alternating access mechanism too. In conclusion, UCP1 has retained all of the key features of mitochondrial carriers, indicating that it operates by a conventional carrier-like mechanism.
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spelling pubmed-53950902017-04-18 The molecular features of uncoupling protein 1 support a conventional mitochondrial carrier-like mechanism Crichton, Paul G. Lee, Yang Kunji, Edmund R.S. Biochimie Article Uncoupling protein 1 (UCP1) is an integral membrane protein found in the mitochondrial inner membrane of brown adipose tissue, and facilitates the process of non-shivering thermogenesis in mammals. Its activation by fatty acids, which overcomes its inhibition by purine nucleotides, leads to an increase in the proton conductance of the inner mitochondrial membrane, short-circuiting the mitochondrion to produce heat rather than ATP. Despite 40 years of intense research, the underlying molecular mechanism of UCP1 is still under debate. The protein belongs to the mitochondrial carrier family of transporters, which have recently been shown to utilise a domain-based alternating-access mechanism, cycling between a cytoplasmic and matrix state to transport metabolites across the inner membrane. Here, we review the protein properties of UCP1 and compare them to those of mitochondrial carriers. UCP1 has the same structural fold as other mitochondrial carriers and, in contrast to past claims, is a monomer, binding one purine nucleotide and three cardiolipin molecules tightly. The protein has a single substrate binding site, which is similar to those of the dicarboxylate and oxoglutarate carriers, but also contains a proton binding site and several hydrophobic residues. As found in other mitochondrial carriers, UCP1 has two conserved salt bridge networks on either side of the central cavity, which regulate access to the substrate binding site in an alternating way. The conserved domain structures and mobile inter-domain interfaces are consistent with an alternating access mechanism too. In conclusion, UCP1 has retained all of the key features of mitochondrial carriers, indicating that it operates by a conventional carrier-like mechanism. 2017-01-03 2017-03 /pmc/articles/PMC5395090/ /pubmed/28057583 http://dx.doi.org/10.1016/j.biochi.2016.12.016 Text en http://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
spellingShingle Article
Crichton, Paul G.
Lee, Yang
Kunji, Edmund R.S.
The molecular features of uncoupling protein 1 support a conventional mitochondrial carrier-like mechanism
title The molecular features of uncoupling protein 1 support a conventional mitochondrial carrier-like mechanism
title_full The molecular features of uncoupling protein 1 support a conventional mitochondrial carrier-like mechanism
title_fullStr The molecular features of uncoupling protein 1 support a conventional mitochondrial carrier-like mechanism
title_full_unstemmed The molecular features of uncoupling protein 1 support a conventional mitochondrial carrier-like mechanism
title_short The molecular features of uncoupling protein 1 support a conventional mitochondrial carrier-like mechanism
title_sort molecular features of uncoupling protein 1 support a conventional mitochondrial carrier-like mechanism
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5395090/
https://www.ncbi.nlm.nih.gov/pubmed/28057583
http://dx.doi.org/10.1016/j.biochi.2016.12.016
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