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Crystal structure of an oxidized mutant of human mitochondrial branched-chain aminotransferase

This study presents the crystal structure of a thiol variant of the human mitochondrial branched-chain aminotransferase protein. Human branched-chain aminotransferase (hBCAT) catalyzes the transamination of the branched-chain amino acids leucine, valine and isoleucine and α-ketoglutarate to their re...

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Autores principales: Herbert, Darius, Gibbs, Synphane, Riddick, Alexys, Conway, Myra, Dong, Ming
Formato: Online Artículo Texto
Lenguaje:English
Publicado: International Union of Crystallography 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6957111/
https://www.ncbi.nlm.nih.gov/pubmed/31929181
http://dx.doi.org/10.1107/S2053230X19016480
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author Herbert, Darius
Gibbs, Synphane
Riddick, Alexys
Conway, Myra
Dong, Ming
author_facet Herbert, Darius
Gibbs, Synphane
Riddick, Alexys
Conway, Myra
Dong, Ming
author_sort Herbert, Darius
collection PubMed
description This study presents the crystal structure of a thiol variant of the human mitochondrial branched-chain aminotransferase protein. Human branched-chain aminotransferase (hBCAT) catalyzes the transamination of the branched-chain amino acids leucine, valine and isoleucine and α-ketoglutarate to their respective α-keto acids and glutamate. hBCAT activity is regulated by a CXXC center located approximately 10 Å from the active site. This redox-active center facilitates recycling between the reduced and oxidized states, representing hBCAT in its active and inactive forms, respectively. Site-directed mutagenesis of the redox sensor (Cys315) results in a significant loss of activity, with no loss of activity reported on the mutation of the resolving cysteine (Cys318), which allows the reversible formation of a disulfide bond between Cys315 and Cys318. The crystal structure of the oxidized form of the C318A variant was used to better understand the contributions of the individual cysteines and their oxidation states. The structure reveals the modified CXXC center in a conformation similar to that in the oxidized wild type, supporting the notion that its regulatory mechanism depends on switching the Cys315 side chain between active and inactive conformations. Moreover, the structure reveals conformational differences in the N-terminal and inter-domain region that may correlate with the inactivated state of the CXXC center.
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spelling pubmed-69571112020-01-16 Crystal structure of an oxidized mutant of human mitochondrial branched-chain aminotransferase Herbert, Darius Gibbs, Synphane Riddick, Alexys Conway, Myra Dong, Ming Acta Crystallogr F Struct Biol Commun Research Communications This study presents the crystal structure of a thiol variant of the human mitochondrial branched-chain aminotransferase protein. Human branched-chain aminotransferase (hBCAT) catalyzes the transamination of the branched-chain amino acids leucine, valine and isoleucine and α-ketoglutarate to their respective α-keto acids and glutamate. hBCAT activity is regulated by a CXXC center located approximately 10 Å from the active site. This redox-active center facilitates recycling between the reduced and oxidized states, representing hBCAT in its active and inactive forms, respectively. Site-directed mutagenesis of the redox sensor (Cys315) results in a significant loss of activity, with no loss of activity reported on the mutation of the resolving cysteine (Cys318), which allows the reversible formation of a disulfide bond between Cys315 and Cys318. The crystal structure of the oxidized form of the C318A variant was used to better understand the contributions of the individual cysteines and their oxidation states. The structure reveals the modified CXXC center in a conformation similar to that in the oxidized wild type, supporting the notion that its regulatory mechanism depends on switching the Cys315 side chain between active and inactive conformations. Moreover, the structure reveals conformational differences in the N-terminal and inter-domain region that may correlate with the inactivated state of the CXXC center. International Union of Crystallography 2020-01-01 /pmc/articles/PMC6957111/ /pubmed/31929181 http://dx.doi.org/10.1107/S2053230X19016480 Text en © Herbert et al. 2020 http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.http://creativecommons.org/licenses/by/4.0/
spellingShingle Research Communications
Herbert, Darius
Gibbs, Synphane
Riddick, Alexys
Conway, Myra
Dong, Ming
Crystal structure of an oxidized mutant of human mitochondrial branched-chain aminotransferase
title Crystal structure of an oxidized mutant of human mitochondrial branched-chain aminotransferase
title_full Crystal structure of an oxidized mutant of human mitochondrial branched-chain aminotransferase
title_fullStr Crystal structure of an oxidized mutant of human mitochondrial branched-chain aminotransferase
title_full_unstemmed Crystal structure of an oxidized mutant of human mitochondrial branched-chain aminotransferase
title_short Crystal structure of an oxidized mutant of human mitochondrial branched-chain aminotransferase
title_sort crystal structure of an oxidized mutant of human mitochondrial branched-chain aminotransferase
topic Research Communications
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6957111/
https://www.ncbi.nlm.nih.gov/pubmed/31929181
http://dx.doi.org/10.1107/S2053230X19016480
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