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RNA‐seq analyses reveal insights into the function of respiratory nitrate reductase of the diazotroph Herbaspirillum seropedicae
Author(s) -
Bonato Paloma,
Batista Marcelo B.,
CamiliosNeto Doumit,
Pankievicz Vânia C. S.,
TadraSfeir Michelle Z.,
Monteiro Rose Adele,
Pedrosa Fabio O.,
Souza Emanuel M.,
Chubatsu Leda S.,
Wassem Roseli,
Rigo Liu Un
Publication year - 2016
Publication title -
environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.954
H-Index - 188
eISSN - 1462-2920
pISSN - 1462-2912
DOI - 10.1111/1462-2920.13422
Subject(s) - diazotroph , biology , nitrate reductase , mutant , microbiology and biotechnology , nitrate , glutamate synthase , bacteria , gene , biochemistry , nitrogen fixation , genetics , ecology , amino acid , glutamine synthetase , glutamine
Summary 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.