Interaction of an IHF-like protein with the Rhizobium etli nifA promoter.
The nifA gene fulfills an essential role in the regulation of nitrogen fixation genes in Rhizobium etli. Transcription analysis of the nifA gene, assessed using promoter deletions, indicated an oxygen-independent expression, threefold higher during symbiosis as compared with free-living conditions. Electrophoretic mobility shift assays using those nifA promoter deletion fragments, which were actively transcribed, demonstrated the specific interaction with R. etli cellular protein(s) resulting in the formation of two DNA-protein complexes. An interacting protein was purified by liquid chromatography on Heparin Sepharose and Mono S columns. The purified 12 kDa R. etli protein cross-reacted with antibodies directed against Escherichia coli integration host factor (IHF). Furthermore, purified E. coli IHF was able to specifically bind to the R. etli nifA promoter region. These results point to an as yet undisclosed function of IHF in the regulation of R. etli nifA expression.
Benhassine
Traki
T
Laboratoire de Biologie Cellulaire et Moléculaire, Faculté des Sciences Biologiques, USTHB, Alger, Algérie.
Fauvart
Maarten
M
Vanderleyden
Jos
J
Michiels
Jan
J
D000907:Antibodies, Bacterial / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics*; D015153:Blotting, Western; D002846:Chromatography, Affinity; D002853:Chromatography, Liquid; D003429:Cross Reactions; D004269:DNA, Bacterial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D034982:Integration Host Factors / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D042163:Rhizobium etli / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics*
D000907:Antibodies, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D034982:Integration Host Factors; C061338:NifA protein, Bacteria; D014157:Transcription Factors; C440502:integration host factor, E coli