RNA-seq analyses reveal insights into the function of respiratory nitrate reductase of the diazotroph Herbaspirillum seropedicae.
Herbaspirillum seropedicae is a nitrogen-fixing β-proteobacterium that associates with roots of gramineous plants. In silico analyses revealed that H. seropedicae genome has genes encoding a putative respiratory (NAR) and an assimilatory nitrate reductase (NAS). To date, little is known about nitrate metabolism in H. seropedicae, and, as this bacterium cannot respire nitrate, the function of NAR remains unknown. This study aimed to investigate the function of NAR in H. seropedicae and how it metabolizes nitrate in a low aerated-condition. RNA-seq transcriptional profiling in the presence of nitrate allowed us to pinpoint genes important for nitrate metabolism in H. seropedicae, including nitrate transporters and regulatory proteins. Additionally, both RNA-seq data and physiological characterization of a mutant in the catalytic subunit of NAR (narG mutant) showed that NAR is not required for nitrate assimilation but is required for: (i) production of high levels of nitrite, (ii) production of NO and (iii) dissipation of redox power, which in turn lead to an increase in carbon consumption. In addition, wheat plants showed an increase in shoot dry weight only when inoculated with H. seropedicae wild type, but not with the narG mutant, suggesting that NAR is important to H. seropedicae-wheat interaction.
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Paloma
P
Bonato
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Marcelo B
MB
Batista
Department of Biochemistry and Biotechnology, Universidade Estadual de Londrina, Londrina, PR, Brazil.
Doumit
D
Camilios-Neto
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Vânia C S
VC
Pankievicz
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Michelle Z
MZ
Tadra-Sfeir
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Rose Adele
RA
Monteiro
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Fabio O
FO
Pedrosa
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Emanuel M
EM
Souza
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Leda S
LS
Chubatsu
Department of Genetics, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Roseli
R
Wassem
Department of Biochemistry and Molecular Biology, Universidade Federal do Paraná, Curitiba, PR, Brazil.
Liu Un
LU
Rigo
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D042803:Herbaspirillum / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D050901:Nitrate Reductase / Q000235:genetics / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism*; D018517:Plant Roots / Q000382:microbiology; D012313:RNA / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014908:Triticum / Q000382:microbiology
D001426:Bacterial Proteins; D009566:Nitrates; D014157:Transcription Factors; D012313:RNA; D050901:Nitrate Reductase