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Salt induction and activation of MtlD, the key enzyme in the synthesis of the compatible solute mannitol in Acinetobacter baumannii

Mannitol is the major compatible solute, next to glutamate, synthesized by the opportunistic human pathogen Acinetobacter baumannii under low water activities. The key enzyme for mannitol biosynthesis, MtlD, was identified. MtlD is highly similar to the bifunctional mannitol‐1‐phosphate dehydrogenas...

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Autores principales: Zeidler, Sabine, Hubloher, Josephine, König, Patricia, Ngu, Ngoc Dinh, Scholz, Anica, Averhoff, Beate, Müller, Volker
Formato: Online Artículo Texto
Lenguaje:English
Publicado: John Wiley and Sons Inc. 2018
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6291793/
https://www.ncbi.nlm.nih.gov/pubmed/29575790
http://dx.doi.org/10.1002/mbo3.614
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author Zeidler, Sabine
Hubloher, Josephine
König, Patricia
Ngu, Ngoc Dinh
Scholz, Anica
Averhoff, Beate
Müller, Volker
author_facet Zeidler, Sabine
Hubloher, Josephine
König, Patricia
Ngu, Ngoc Dinh
Scholz, Anica
Averhoff, Beate
Müller, Volker
author_sort Zeidler, Sabine
collection PubMed
description Mannitol is the major compatible solute, next to glutamate, synthesized by the opportunistic human pathogen Acinetobacter baumannii under low water activities. The key enzyme for mannitol biosynthesis, MtlD, was identified. MtlD is highly similar to the bifunctional mannitol‐1‐phosphate dehydrogenase/phosphatase from Acinetobacter baylyi. After deletion of the mtlD gene from A. baumannii ATCC 19606(T) cells no longer accumulated mannitol and growth was completely impaired at high salt. Addition of glycine betaine restored growth, demonstrating that mannitol is an important compatible solute in the human pathogen. MtlD was heterologously produced and purified. Enzyme activity was strictly salt dependent. Highest stimulation was reached at 600 mmol/L NaCl. Addition of different sodium as well as potassium salts restored activity, with highest stimulations up to 41 U/mg protein by sodium glutamate. In contrast, an increase in osmolarity by addition of sugars did not restore activity. Regulation of mannitol synthesis was also assayed at the transcriptional level. Reporter gene assays revealed that expression of mtlD is strongly dependent on high osmolarity, not discriminating between different salts or sugars. The presence of glycine betaine or its precursor choline repressed promoter activation. These data indicate a dual regulation of mannitol production in A. baumannii, at the transcriptional and the enzymatic level, depending on high osmolarity.
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spelling pubmed-62917932018-12-18 Salt induction and activation of MtlD, the key enzyme in the synthesis of the compatible solute mannitol in Acinetobacter baumannii Zeidler, Sabine Hubloher, Josephine König, Patricia Ngu, Ngoc Dinh Scholz, Anica Averhoff, Beate Müller, Volker Microbiologyopen Original Articles Mannitol is the major compatible solute, next to glutamate, synthesized by the opportunistic human pathogen Acinetobacter baumannii under low water activities. The key enzyme for mannitol biosynthesis, MtlD, was identified. MtlD is highly similar to the bifunctional mannitol‐1‐phosphate dehydrogenase/phosphatase from Acinetobacter baylyi. After deletion of the mtlD gene from A. baumannii ATCC 19606(T) cells no longer accumulated mannitol and growth was completely impaired at high salt. Addition of glycine betaine restored growth, demonstrating that mannitol is an important compatible solute in the human pathogen. MtlD was heterologously produced and purified. Enzyme activity was strictly salt dependent. Highest stimulation was reached at 600 mmol/L NaCl. Addition of different sodium as well as potassium salts restored activity, with highest stimulations up to 41 U/mg protein by sodium glutamate. In contrast, an increase in osmolarity by addition of sugars did not restore activity. Regulation of mannitol synthesis was also assayed at the transcriptional level. Reporter gene assays revealed that expression of mtlD is strongly dependent on high osmolarity, not discriminating between different salts or sugars. The presence of glycine betaine or its precursor choline repressed promoter activation. These data indicate a dual regulation of mannitol production in A. baumannii, at the transcriptional and the enzymatic level, depending on high osmolarity. John Wiley and Sons Inc. 2018-03-24 /pmc/articles/PMC6291793/ /pubmed/29575790 http://dx.doi.org/10.1002/mbo3.614 Text en © 2018 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd. This is an open access article under the terms of the http://creativecommons.org/licenses/by/4.0/ License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
spellingShingle Original Articles
Zeidler, Sabine
Hubloher, Josephine
König, Patricia
Ngu, Ngoc Dinh
Scholz, Anica
Averhoff, Beate
Müller, Volker
Salt induction and activation of MtlD, the key enzyme in the synthesis of the compatible solute mannitol in Acinetobacter baumannii
title Salt induction and activation of MtlD, the key enzyme in the synthesis of the compatible solute mannitol in Acinetobacter baumannii
title_full Salt induction and activation of MtlD, the key enzyme in the synthesis of the compatible solute mannitol in Acinetobacter baumannii
title_fullStr Salt induction and activation of MtlD, the key enzyme in the synthesis of the compatible solute mannitol in Acinetobacter baumannii
title_full_unstemmed Salt induction and activation of MtlD, the key enzyme in the synthesis of the compatible solute mannitol in Acinetobacter baumannii
title_short Salt induction and activation of MtlD, the key enzyme in the synthesis of the compatible solute mannitol in Acinetobacter baumannii
title_sort salt induction and activation of mtld, the key enzyme in the synthesis of the compatible solute mannitol in acinetobacter baumannii
topic Original Articles
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6291793/
https://www.ncbi.nlm.nih.gov/pubmed/29575790
http://dx.doi.org/10.1002/mbo3.614
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