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Enhanced oxygen consumption in Herbaspirillum seropedicae fnr mutants leads to increased NifA mediated transcriptional activation

BACKGROUND: Orthologous proteins of the Crp/Fnr family have been previously implicated in controlling expression and/or activity of the NifA transcriptional activator in some diazotrophs. This study aimed to address the role of three Fnr-like proteins from H. seropedicae SmR1 in controlling NifA act...

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Autores principales: Batista, Marcelo Bueno, Wassem, Roseli, de Oliveira Pedrosa, Fábio, de Souza, Emanuel Maltempi, Dixon, Ray, Monteiro, Rose Adele
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4422417/
https://www.ncbi.nlm.nih.gov/pubmed/25947294
http://dx.doi.org/10.1186/s12866-015-0432-6
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author Batista, Marcelo Bueno
Wassem, Roseli
de Oliveira Pedrosa, Fábio
de Souza, Emanuel Maltempi
Dixon, Ray
Monteiro, Rose Adele
author_facet Batista, Marcelo Bueno
Wassem, Roseli
de Oliveira Pedrosa, Fábio
de Souza, Emanuel Maltempi
Dixon, Ray
Monteiro, Rose Adele
author_sort Batista, Marcelo Bueno
collection PubMed
description BACKGROUND: Orthologous proteins of the Crp/Fnr family have been previously implicated in controlling expression and/or activity of the NifA transcriptional activator in some diazotrophs. This study aimed to address the role of three Fnr-like proteins from H. seropedicae SmR1 in controlling NifA activity and consequent NifA-mediated transcription activation. RESULTS: The activity of NifA-dependent transcriptional fusions (nifA::lacZ and nifB::lacZ) was analysed in a series of H. seropedicae fnr deletion mutant backgrounds. We found that combined deletions in both the fnr1 and fnr3 genes lead to higher expression of both the nifA and nifB genes and also an increased level of nifH transcripts. Expression profiles of nifB under different oxygen concentrations, together with oxygen consumption measurements suggest that the triple fnr mutant has higher respiratory activity when compared to the wild type, which we believe to be responsible for greater stability of the oxygen sensitive NifA protein. This conclusion was further substantiated by measuring the levels of NifA protein and its activity in fnr deletion strains in comparison with the wild-type. CONCLUSIONS: Fnr proteins are indirectly involved in controlling the activity of NifA in H. seropedicae, probably as a consequence of their influence on respiratory activity in relation to oxygen availability. Additionally we can suggest that there is some redundancy in the physiological function of the three Fnr paralogs in this organism, since altered respiration and effects on NifA activity are only observed in deletion strains lacking both fnr1 and fnr3. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12866-015-0432-6) contains supplementary material, which is available to authorized users.
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spelling pubmed-44224172015-05-07 Enhanced oxygen consumption in Herbaspirillum seropedicae fnr mutants leads to increased NifA mediated transcriptional activation Batista, Marcelo Bueno Wassem, Roseli de Oliveira Pedrosa, Fábio de Souza, Emanuel Maltempi Dixon, Ray Monteiro, Rose Adele BMC Microbiol Research Article BACKGROUND: Orthologous proteins of the Crp/Fnr family have been previously implicated in controlling expression and/or activity of the NifA transcriptional activator in some diazotrophs. This study aimed to address the role of three Fnr-like proteins from H. seropedicae SmR1 in controlling NifA activity and consequent NifA-mediated transcription activation. RESULTS: The activity of NifA-dependent transcriptional fusions (nifA::lacZ and nifB::lacZ) was analysed in a series of H. seropedicae fnr deletion mutant backgrounds. We found that combined deletions in both the fnr1 and fnr3 genes lead to higher expression of both the nifA and nifB genes and also an increased level of nifH transcripts. Expression profiles of nifB under different oxygen concentrations, together with oxygen consumption measurements suggest that the triple fnr mutant has higher respiratory activity when compared to the wild type, which we believe to be responsible for greater stability of the oxygen sensitive NifA protein. This conclusion was further substantiated by measuring the levels of NifA protein and its activity in fnr deletion strains in comparison with the wild-type. CONCLUSIONS: Fnr proteins are indirectly involved in controlling the activity of NifA in H. seropedicae, probably as a consequence of their influence on respiratory activity in relation to oxygen availability. Additionally we can suggest that there is some redundancy in the physiological function of the three Fnr paralogs in this organism, since altered respiration and effects on NifA activity are only observed in deletion strains lacking both fnr1 and fnr3. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12866-015-0432-6) contains supplementary material, which is available to authorized users. BioMed Central 2015-05-07 /pmc/articles/PMC4422417/ /pubmed/25947294 http://dx.doi.org/10.1186/s12866-015-0432-6 Text en © Batista et al.; licensee BioMed Central. 2015 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research Article
Batista, Marcelo Bueno
Wassem, Roseli
de Oliveira Pedrosa, Fábio
de Souza, Emanuel Maltempi
Dixon, Ray
Monteiro, Rose Adele
Enhanced oxygen consumption in Herbaspirillum seropedicae fnr mutants leads to increased NifA mediated transcriptional activation
title Enhanced oxygen consumption in Herbaspirillum seropedicae fnr mutants leads to increased NifA mediated transcriptional activation
title_full Enhanced oxygen consumption in Herbaspirillum seropedicae fnr mutants leads to increased NifA mediated transcriptional activation
title_fullStr Enhanced oxygen consumption in Herbaspirillum seropedicae fnr mutants leads to increased NifA mediated transcriptional activation
title_full_unstemmed Enhanced oxygen consumption in Herbaspirillum seropedicae fnr mutants leads to increased NifA mediated transcriptional activation
title_short Enhanced oxygen consumption in Herbaspirillum seropedicae fnr mutants leads to increased NifA mediated transcriptional activation
title_sort enhanced oxygen consumption in herbaspirillum seropedicae fnr mutants leads to increased nifa mediated transcriptional activation
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4422417/
https://www.ncbi.nlm.nih.gov/pubmed/25947294
http://dx.doi.org/10.1186/s12866-015-0432-6
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