The Mesorhizobium huakuii transcriptional regulator AbiEi plays a critical role in nodulation and is important for bacterial stress response.
Mesorhizobium huakuii
RNA-Seq analysis of nodule bacteroids
Symbiosis nitrogen fixation
Transcriptional regulator AbiEi
Type IV toxin–antitoxin system
Journal
BMC microbiology
ISSN: 1471-2180
Titre abrégé: BMC Microbiol
Pays: England
ID NLM: 100966981
Informations de publication
Date de publication:
12 09 2021
12 09 2021
Historique:
received:
04
05
2021
accepted:
28
08
2021
entrez:
13
9
2021
pubmed:
14
9
2021
medline:
7
1
2022
Statut:
epublish
Résumé
Bacterial abortive infection (Abi) systems are type IV toxin-antitoxin (TA) system, which could elicit programmed cell death and constitute a native survival strategy of pathogenic bacteria under various stress conditions. However, no rhizobial AbiE family TA system has been reported so far. Here, a M. huakuii AbiE TA system was identified and characterized. A mutation in M. huakuii abiEi gene, encoding an adjacent GntR-type transcriptional regulator, was generated by homologous recombination. The abiEi mutant strain grew less well in rich TY medium, and displayed increased antioxidative capacity and enhanced gentamicin resistance, indicating the abiEi operon was negatively regulated by the antitoxin AbiEi in response to the oxidative stress and a particular antibiotic. The mRNA expression of abiEi gene was significantly up-regulated during Astragalus sinicus nodule development. The abiEi mutant was severely impaired in its competitive ability in rhizosphere colonization, and was defective in nodulation with 97% reduction in nitrogen-fixing capacity. The mutant infected nodule cells contained vacuolation and a small number of abnormal bacteroids with senescence character. RNA-seq experiment revealed it had 5 up-regulated and 111 down-regulated genes relative to wild type. Of these down-regulated genes, 21 are related to symbiosis nitrogen fixation and nitrogen mechanism, 16 are involved in the electron transport chain and antioxidant responses, and 12 belong to type VI secretion system (T6SS). M. huakuii AbiEi behaves as a key transcriptional regulator mediating root nodule symbiosis.
Sections du résumé
BACKGROUND
Bacterial abortive infection (Abi) systems are type IV toxin-antitoxin (TA) system, which could elicit programmed cell death and constitute a native survival strategy of pathogenic bacteria under various stress conditions. However, no rhizobial AbiE family TA system has been reported so far. Here, a M. huakuii AbiE TA system was identified and characterized.
RESULTS
A mutation in M. huakuii abiEi gene, encoding an adjacent GntR-type transcriptional regulator, was generated by homologous recombination. The abiEi mutant strain grew less well in rich TY medium, and displayed increased antioxidative capacity and enhanced gentamicin resistance, indicating the abiEi operon was negatively regulated by the antitoxin AbiEi in response to the oxidative stress and a particular antibiotic. The mRNA expression of abiEi gene was significantly up-regulated during Astragalus sinicus nodule development. The abiEi mutant was severely impaired in its competitive ability in rhizosphere colonization, and was defective in nodulation with 97% reduction in nitrogen-fixing capacity. The mutant infected nodule cells contained vacuolation and a small number of abnormal bacteroids with senescence character. RNA-seq experiment revealed it had 5 up-regulated and 111 down-regulated genes relative to wild type. Of these down-regulated genes, 21 are related to symbiosis nitrogen fixation and nitrogen mechanism, 16 are involved in the electron transport chain and antioxidant responses, and 12 belong to type VI secretion system (T6SS).
CONCLUSIONS
M. huakuii AbiEi behaves as a key transcriptional regulator mediating root nodule symbiosis.
Identifiants
pubmed: 34511061
doi: 10.1186/s12866-021-02304-0
pii: 10.1186/s12866-021-02304-0
pmc: PMC8436566
doi:
Substances chimiques
Bacterial Proteins
0
Transcription Factors
0
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
245Informations de copyright
© 2021. The Author(s).
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