NtcA is responsible for accumulation of the small isoform of ferredoxin:NADP oxidoreductase

• Published in: Microbiology (Society for General Microbiology) 2014-04, Vol.160 (Pt 4), p.789-794
• Main Authors: Omairi-Nasser, Amin, Galmozzi, Carla V, Latifi, Amel, Muro-Pastor, M Isabel, Ajlani, Ghada
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - metabolism; Binding Sites; DNA Mutational Analysis; DNA-Binding Proteins - metabolism; Ferredoxin-NADP Reductase - metabolism; Flavoproteins - metabolism; Gene Expression; Gene Expression Regulation, Bacterial; Promoter Regions, Genetic; Protein Isoforms - metabolism; Synechocystis - enzymology; Synechocystis - genetics; Transcription Factors - metabolism; Transcription, Genetic
• ISSN: 1350-0872; 1465-2080
• DOI: 10.1099/mic.0.076042-0

In several cyanobacteria, petH, the gene encoding ferredoxin:NADP oxidoreductase (FNR), is transcribed from at least two promoters depending on growth conditions. Two transcripts (short and long) are translated from two different translation initiation sites, resulting in two isoforms (large and small, respectively). Here, we show that in Synechocystis PCC6803 the global transcriptional regulator NtcA activates transcription from the distal petH promoter. Modification of the NtcA-binding site prevents NtcA binding to the promoter in vitro and abolishes accumulation of the small isoform of FNR in vivo. We also demonstrate that a similar petH transcription and translation regime occurs in other cyanobacteria. The conditions under which this system operates provide hints for the function of each FNR isoform.