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Patient mutations in human ATP:cob(I)alamin adenosyltransferase differentially affect its catalytic versus chaperone functions

Human ATP:cob(I)alamin adenosyltransferase (ATR) is a mitochondrial enzyme that catalyzes an adenosyl transfer to cob(I)alamin, synthesizing 5′-deoxyadenosylcobalamin (AdoCbl) or coenzyme B(12). ATR is also a chaperone that escorts AdoCbl, transferring it to methylmalonyl-CoA mutase, which is import...

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Autores principales: Gouda, Harsha, Mascarenhas, Romila, Pillay, Shubhadra, Ruetz, Markus, Koutmos, Markos, Banerjee, Ruma
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Biochemistry and Molecular Biology 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8633584/
https://www.ncbi.nlm.nih.gov/pubmed/34757128
http://dx.doi.org/10.1016/j.jbc.2021.101373
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author Gouda, Harsha
Mascarenhas, Romila
Pillay, Shubhadra
Ruetz, Markus
Koutmos, Markos
Banerjee, Ruma
author_facet Gouda, Harsha
Mascarenhas, Romila
Pillay, Shubhadra
Ruetz, Markus
Koutmos, Markos
Banerjee, Ruma
author_sort Gouda, Harsha
collection PubMed
description Human ATP:cob(I)alamin adenosyltransferase (ATR) is a mitochondrial enzyme that catalyzes an adenosyl transfer to cob(I)alamin, synthesizing 5′-deoxyadenosylcobalamin (AdoCbl) or coenzyme B(12). ATR is also a chaperone that escorts AdoCbl, transferring it to methylmalonyl-CoA mutase, which is important in propionate metabolism. Mutations in ATR lead to methylmalonic aciduria type B, an inborn error of B(12) metabolism. Our previous studies have furnished insights into how ATR protein dynamics influence redox-linked cobalt coordination chemistry, controlling its catalytic versus chaperone functions. In this study, we have characterized three patient mutations at two conserved active site residues in human ATR, R190C/H, and E193K and obtained crystal structures of R190C and E193K variants, which display only subtle structural changes. All three mutations were found to weaken affinities for the cob(II)alamin substrate and the AdoCbl product and increase K(M(ATP)). (31)P NMR studies show that binding of the triphosphate product, formed during the adenosylation reaction, is also weakened. However, although the k(cat) of this reaction is significantly diminished for the R190C/H mutants, it is comparable with the WT enzyme for the E193K variant, revealing the catalytic importance of Arg-190. Furthermore, although the E193K mutation selectively impairs the chaperone function by promoting product release into solution, its catalytic function might be unaffected at physiological ATP concentrations. In contrast, the R190C/H mutations affect both the catalytic and chaperoning activities of ATR. Because the E193K mutation spares the catalytic activity of ATR, our data suggest that the patients carrying this mutation are more likely to be responsive to cobalamin therapy.
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spelling pubmed-86335842021-12-06 Patient mutations in human ATP:cob(I)alamin adenosyltransferase differentially affect its catalytic versus chaperone functions Gouda, Harsha Mascarenhas, Romila Pillay, Shubhadra Ruetz, Markus Koutmos, Markos Banerjee, Ruma J Biol Chem Research Article Human ATP:cob(I)alamin adenosyltransferase (ATR) is a mitochondrial enzyme that catalyzes an adenosyl transfer to cob(I)alamin, synthesizing 5′-deoxyadenosylcobalamin (AdoCbl) or coenzyme B(12). ATR is also a chaperone that escorts AdoCbl, transferring it to methylmalonyl-CoA mutase, which is important in propionate metabolism. Mutations in ATR lead to methylmalonic aciduria type B, an inborn error of B(12) metabolism. Our previous studies have furnished insights into how ATR protein dynamics influence redox-linked cobalt coordination chemistry, controlling its catalytic versus chaperone functions. In this study, we have characterized three patient mutations at two conserved active site residues in human ATR, R190C/H, and E193K and obtained crystal structures of R190C and E193K variants, which display only subtle structural changes. All three mutations were found to weaken affinities for the cob(II)alamin substrate and the AdoCbl product and increase K(M(ATP)). (31)P NMR studies show that binding of the triphosphate product, formed during the adenosylation reaction, is also weakened. However, although the k(cat) of this reaction is significantly diminished for the R190C/H mutants, it is comparable with the WT enzyme for the E193K variant, revealing the catalytic importance of Arg-190. Furthermore, although the E193K mutation selectively impairs the chaperone function by promoting product release into solution, its catalytic function might be unaffected at physiological ATP concentrations. In contrast, the R190C/H mutations affect both the catalytic and chaperoning activities of ATR. Because the E193K mutation spares the catalytic activity of ATR, our data suggest that the patients carrying this mutation are more likely to be responsive to cobalamin therapy. American Society for Biochemistry and Molecular Biology 2021-10-29 /pmc/articles/PMC8633584/ /pubmed/34757128 http://dx.doi.org/10.1016/j.jbc.2021.101373 Text en © 2021 The Authors https://creativecommons.org/licenses/by/4.0/This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Research Article
Gouda, Harsha
Mascarenhas, Romila
Pillay, Shubhadra
Ruetz, Markus
Koutmos, Markos
Banerjee, Ruma
Patient mutations in human ATP:cob(I)alamin adenosyltransferase differentially affect its catalytic versus chaperone functions
title Patient mutations in human ATP:cob(I)alamin adenosyltransferase differentially affect its catalytic versus chaperone functions
title_full Patient mutations in human ATP:cob(I)alamin adenosyltransferase differentially affect its catalytic versus chaperone functions
title_fullStr Patient mutations in human ATP:cob(I)alamin adenosyltransferase differentially affect its catalytic versus chaperone functions
title_full_unstemmed Patient mutations in human ATP:cob(I)alamin adenosyltransferase differentially affect its catalytic versus chaperone functions
title_short Patient mutations in human ATP:cob(I)alamin adenosyltransferase differentially affect its catalytic versus chaperone functions
title_sort patient mutations in human atp:cob(i)alamin adenosyltransferase differentially affect its catalytic versus chaperone functions
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8633584/
https://www.ncbi.nlm.nih.gov/pubmed/34757128
http://dx.doi.org/10.1016/j.jbc.2021.101373
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