Cloning, sequencing and transcriptional regulation of the draT and draG genes of Azospirillum lipoferum FS.
From Azospirillum lipoferum (Al) FS, a nitrogen-fixing bacterium isolated from the rhizosphere of rice, we cloned and sequenced draT, encoding dinitrogenase reductase ADP-ribosyltransferase, and draG, encoding dinitrogenase reductase-activating glycohydrolase. The nucleotide sequences of draTG showed extensive similarity to the same genes from Azospirillum brasilense, Rhodospirillum rubrum and Rhodobacter capsulatus, and they are assumed to be co-transcribed as a single operon. When this draTG operon was introduced into Klebsiella oxytoca, this organism acquired the ability to respond to extracellular NH(+4) ions with reversible inhibition of nitrogenase activity, similar to that seen in Al FS. We constructed a plasmid containing a draT::lacZ gene fusion and found that beta-galactosidase activity was detected under microaerobic conditions, regardless of NH(+4) concentration, but not under aerobic conditions. This indicates that the transcription of draTG responds to the level of oxygen, but not to that of NH(+4) ions.
Inoue
A
A
Department of Biotechnology, University of Tokyo, Japan.
Shigematsu
T
T
Hidaka
M
M
Masaki
H
H
Uozumi
T
T
D036002:ADP Ribose Transferases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D016949:Azospirillum / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006026:Glycoside Hydrolases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases; D016366:Open Reading Frames; D009876:Operon / Q000235:genetics; D014158:Transcription, Genetic
D036002:ADP Ribose Transferases; C057637:dinitrogenase reductase ADP-ribosyltransferase; D006026:Glycoside Hydrolases; D009699:N-Glycosyl Hydrolases; C036091:ADP-ribosyl-(dinitrogen reductase) hydrolase