01903naa a2200349 a 450000100080000000500110000800800410001910000190006024500910007926000090017052009570017965000100113665000130114665000090115965000140116865300080118265300080119065300390119865300290123770000270126670000220129370000230131570000160133870000190135470000190137370000170139270000160140970000180142570000170144370000170146077300760147716210901999-06-10       1997    bl uuuu     u00u1 u    #d1 aPEDROSA, F. O.  aStructural organization and regulation of the Nif genes of Herbaspirillum seropedicae.  c1997  aThe promoter regions of nifA and nifH genes of Herbaspirillum seropedicae have been isolated and investigated, and the nifA promoter has been characterized in detail. Both regions contain a -24/-12 type promoter and nifA-binding sites; the nifA promoter also has an NtrC-binding site. The nifA expression is activated by NtrC and repressed by ammonium ions but not by oxygen. When the NtrC-binding site was deleted nifA expression was NifA-dependent. The native NifA protein of H. seropedicae was unable to activate nifH expression in Escherichia coli whereas a truncated protein, lacking the N-terminal domain was able to activate nifH expression in the absence of oxygen and presence of iron, indicating that the N-terminal domain regulates NifA activity. The truncated protein also activates nifH in Azospirillum brasilense in the presence or absence of ammonium ions. This suggests that the N-terminal domain senses the nitrogen status of the cell.  agenes  aproteins  aGene  aProteína  aBNF  aFBN  aFixação biologica de nitrogênio  aNitrogen fixing bacteria1 aTEIXEIRA, K. R. dos S.1 aMACHADO, I. M. P.1 aSTEFFENS, M. B. R.1 aKLASSEN, G.1 aBENELLI, E. M.1 aMACHADO, H. B.1 aFUNAYAMA, S.1 aRIGO, L. U.1 aISHIDA, M. L.1 aYATES, M. G.1 aSOUZA, E. M.  tSoil Biology and Biochemistry, Oxfordgv. 29, n. 5/6, p. 843-846, 1997.