Dual control of the nodA operon of Azorhizobium caulinodans ORS571 by a nod box and a NifA-sigma54-type promoter.
Earlier studies have shown that the Azorhizohium caulinodans nodA promoter is controlled by a host plant-derived flavonoid signal via the transcription activator NodD. Here, we report that the transcription of the nodA operon is also under the control of NifA-RpoN. A NifA-sigma54-type promoter, P2nodA, is present upstream of the nod-box consensus motif of the nodA gene and directs expression of a nodA-uidA reporter gene both in free-living bacteria under nitrogen fixation conditions and in bacteroids. Mutation of P2nodA reduced, under certain conditions, the efficiency of nodulation and accelerated nodule senescence, suggesting that the dual control may help to optimize nodule initiation and function in the natural context of the symbiosis.
Gao
M
M
Departement Plantengenetica, Vlaams Interuniversitair Instituut voor Biotechnologie, Universiteit Gent, Belgium.
D'Haeze
W
W
De Rycke
R
R
Holsters
M
M
D000217:Acyltransferases / Q000235:genetics*; D020599:Azorhizobium caulinodans / Q000235:genetics*; D001412:Bacillus subtilis / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D007887:Fabaceae / Q000235:genetics / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D007700:Kinetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009876:Operon; D018517:Plant Roots / Q000382:microbiology; D010946:Plants, Medicinal; D010957:Plasmids; D011401:Promoter Regions, Genetic; D051877:RNA Polymerase Sigma 54; D015183:Restriction Mapping; D016415:Sequence Alignment; D017384:Sequence Deletion; D012689:Sequence Homology, Nucleic Acid; D012808:Sigma Factor / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics*
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C061338:NifA protein, Bacteria; D012808:Sigma Factor; D014157:Transcription Factors; D000217:Acyltransferases; C060770:NodA protein, Rhizobiales; D012321:DNA-Directed RNA Polymerases; D051877:RNA Polymerase Sigma 54