Cloning, sequencing, and regulation of the global nitrogen regulator gene ntcA in the unicellular diazotrophic cyanobacterium Cyanothece sp. strain BH68K.

摘要: In cyanobacteria, ammonium represses expression of proteins involved in nitrogen fixation and assimilation. The global regulator gene ntcA encodes a DNA-binding protein, NtcA, that is transcriptional activator genes subject to control. We report the cloning sequencing from nitrogen-fixing unicellular cyanobacterium, Cyanothece sp. strain BH68K. comprises 678 nucleotides, deduced NtcA protein contains 226 amino acids with predicted molecular weight 25,026. addition, mRNA levels were measured cells grown under different regimes. Under conditions, transcripts weakly expressed. Furthermore, was diminished or inversely proportional nifHDK expression. Conversely, increased nitrate-grown cells, concentration-dependent increase seen ammonium-grown up 1 mM NH4Cl. These results indicate more assimilation than also imply rhythmic transcription may be control circadian clock.