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Functional Characterization of Two M42 Aminopeptidases Erroneously Annotated as Cellulases

Several aminopeptidases of the M42 family have been described as tetrahedral-shaped dodecameric (TET) aminopeptidases. A current hypothesis suggests that these enzymes are involved, along with the tricorn peptidase, in degrading peptides produced by the proteasome. Yet the M42 family remains ill def...

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Autores principales: Dutoit, Raphaël, Brandt, Nathalie, Legrain, Christianne, Bauvois, Cédric
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3511314/
https://www.ncbi.nlm.nih.gov/pubmed/23226342
http://dx.doi.org/10.1371/journal.pone.0050639
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author Dutoit, Raphaël
Brandt, Nathalie
Legrain, Christianne
Bauvois, Cédric
author_facet Dutoit, Raphaël
Brandt, Nathalie
Legrain, Christianne
Bauvois, Cédric
author_sort Dutoit, Raphaël
collection PubMed
description Several aminopeptidases of the M42 family have been described as tetrahedral-shaped dodecameric (TET) aminopeptidases. A current hypothesis suggests that these enzymes are involved, along with the tricorn peptidase, in degrading peptides produced by the proteasome. Yet the M42 family remains ill defined, as some members have been annotated as cellulases because of their homology with CelM, formerly described as an endoglucanase of Clostridium thermocellum. Here we describe the catalytic functions and substrate profiles CelM and of TmPep1050, the latter having been annotated as an endoglucanase of Thermotoga maritima. Both enzymes were shown to catalyze hydrolysis of nonpolar aliphatic L-amino acid-pNA substrates, the L-leucine derivative appearing as the best substrate. No significant endoglucanase activity was measured, either for TmPep1050 or CelM. Addition of cobalt ions enhanced the activity of both enzymes significantly, while both the chelating agent EDTA and bestatin, a specific inhibitor of metalloaminopeptidases, proved inhibitory. Our results strongly suggest that one should avoid annotating members of the M42 aminopeptidase family as cellulases. In an updated assessment of the distribution of M42 aminopeptidases, we found TET aminopeptidases to be distributed widely amongst archaea and bacteria. We additionally observed that several phyla lack both TET and tricorn. This suggests that other complexes may act downstream from the proteasome.
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spelling pubmed-35113142012-12-05 Functional Characterization of Two M42 Aminopeptidases Erroneously Annotated as Cellulases Dutoit, Raphaël Brandt, Nathalie Legrain, Christianne Bauvois, Cédric PLoS One Research Article Several aminopeptidases of the M42 family have been described as tetrahedral-shaped dodecameric (TET) aminopeptidases. A current hypothesis suggests that these enzymes are involved, along with the tricorn peptidase, in degrading peptides produced by the proteasome. Yet the M42 family remains ill defined, as some members have been annotated as cellulases because of their homology with CelM, formerly described as an endoglucanase of Clostridium thermocellum. Here we describe the catalytic functions and substrate profiles CelM and of TmPep1050, the latter having been annotated as an endoglucanase of Thermotoga maritima. Both enzymes were shown to catalyze hydrolysis of nonpolar aliphatic L-amino acid-pNA substrates, the L-leucine derivative appearing as the best substrate. No significant endoglucanase activity was measured, either for TmPep1050 or CelM. Addition of cobalt ions enhanced the activity of both enzymes significantly, while both the chelating agent EDTA and bestatin, a specific inhibitor of metalloaminopeptidases, proved inhibitory. Our results strongly suggest that one should avoid annotating members of the M42 aminopeptidase family as cellulases. In an updated assessment of the distribution of M42 aminopeptidases, we found TET aminopeptidases to be distributed widely amongst archaea and bacteria. We additionally observed that several phyla lack both TET and tricorn. This suggests that other complexes may act downstream from the proteasome. Public Library of Science 2012-11-30 /pmc/articles/PMC3511314/ /pubmed/23226342 http://dx.doi.org/10.1371/journal.pone.0050639 Text en © 2012 Dutoit et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
spellingShingle Research Article
Dutoit, Raphaël
Brandt, Nathalie
Legrain, Christianne
Bauvois, Cédric
Functional Characterization of Two M42 Aminopeptidases Erroneously Annotated as Cellulases
title Functional Characterization of Two M42 Aminopeptidases Erroneously Annotated as Cellulases
title_full Functional Characterization of Two M42 Aminopeptidases Erroneously Annotated as Cellulases
title_fullStr Functional Characterization of Two M42 Aminopeptidases Erroneously Annotated as Cellulases
title_full_unstemmed Functional Characterization of Two M42 Aminopeptidases Erroneously Annotated as Cellulases
title_short Functional Characterization of Two M42 Aminopeptidases Erroneously Annotated as Cellulases
title_sort functional characterization of two m42 aminopeptidases erroneously annotated as cellulases
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3511314/
https://www.ncbi.nlm.nih.gov/pubmed/23226342
http://dx.doi.org/10.1371/journal.pone.0050639
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