Open AccessPotential roles for the glnB and ntrYX genes in Azospirillum brasilense
Author(s) -
Vitorino Josiane C,
Steffens M.Berenice R,
Machado Hidevaldo B,
Yates M.Geoffrey,
Souza Emanuel M,
Pedrosa Fábio O
Publication year - 2001
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.2001.tb10757.x
Subject(s) - azospirillum brasilense , nitrogenase , mutant , plasmid , biology , nitrogen fixation , nitrate reductase , microbiology and biotechnology , gene , bacteria , biochemistry , genetics , enzyme
Three Azospirillum brasilense mutants constitutive for nitrogen fixation (Nif C ) in the presence of NH 4 + and deficient in nitrate‐dependent growth were used as tools to define the roles of the glnB and ntrYX genes in this organism. Mutant HM14 was complemented for nitrate‐dependent growth and NH 4 + regulation of nitrogenase by plasmid pL46 which contains the ntrYX genes of A. brasilense . Mutant HM26 was restored for NH 4 + regulation and nitrate‐dependent growth by plasmid pJC1, carrying the A. brasilense glnB gene expressed from a constitutive promoter. Mutant HM053, on the other hand, was not complemented for NH 4 + regulation of nitrogenase and nitrate‐dependent growth by both plasmids pJCI and pL46. The levels and control of glutamine synthetase activity of all mutants were not affected by both plasmids pL46 ( ntrYX ) and pJC1 ( glnB ). These results support the characterization of strains HM14 as an ntrYX mutant and strain HM26 as a glnB mutant and the involvement of ntrYX and glnB in the regulation of the general nitrogen metabolism in A. brasilense .