title: A larger transcript is required for the synthesis of the smaller isoform of ferredoxin:NADP oxidoreductase.
abstract: Ferredoxin:NADP oxidoreductases (FNRs) constitute a family of flavoenzymes that catalyse the exchange of electrons between ferredoxin and NADP(H). In cyanobacteria FNR provides NADPH for photoautotrophic metabolism, but the enzyme is also capable of oxidizing NADPH providing reduced ferredoxin. In the cyanobacterium Synechocystis sp. strain PCC6803, the unique petH gene has two translation products depending on growth conditions. As a consequence two isoforms of the FNR accumulate - FNR(L) and FNR(S) . In the present work, analysis of petH expression reveals that different transcriptional start points (tsp) are responsible for this differential translation initiation. Under standard conditions (where FNR(L) accumulates), two tsps were found at -52 and -34 relative to the first translation start site. Under nitrogen-starvation conditions (where FNR(S) accumulates) a tsp was mapped at -126 relative to the first translation start site. Therefore, the transcript responsible for FNR(S) translation is longer than that producing FNR(L) . In addition, expression of the short or long transcript in E. coli resulted in the accumulation of FNR(L) or FNR(S) respectively. This result demonstrates that translation can initiate at two different sites, 336-bases apart (ATG-1 to ATG-113), depending only on the 5'UTR structure.
authors.affiliation: Institut de Biologie et de Technologie de Saclay, Centre National de la Recherche Scientifique and Commissariat à l'Energie Atomique, 91191 Gif-sur-Yvette.
authors.forename: Amin
authors.initials: A
authors.lastname: Omairi-Nasser
authors.forename: Adrienne Gomez
authors.initials: AG
authors.lastname: de Gracia
authors.forename: Ghada
authors.initials: G
authors.lastname: Ajlani
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D018387:Codon, Initiator; D004926:Escherichia coli / Q000235:genetics; D005287:Ferredoxin-NADP Reductase / Q000235:genetics / Q000378:metabolism*; D005288:Ferredoxins / Q000378:metabolism; D005420:Flavoproteins / Q000235:genetics / Q000378:metabolism; D055029:Inverted Repeat Sequences / Q000235:genetics; D007527:Isoenzymes / Q000096:biosynthesis / Q000235:genetics; D009249:NADP / Q000378:metabolism; D009584:Nitrogen / Q000172:deficiency; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D017384:Sequence Deletion; D046939:Synechocystis / Q000201:enzymology* / Q000235:genetics; D014158:Transcription, Genetic
chemical_list: D020121:5' Untranslated Regions; D001426:Bacterial Proteins; D018387:Codon, Initiator; D005288:Ferredoxins; D005420:Flavoproteins; D007527:Isoenzymes; D012333:RNA, Messenger; D009249:NADP; D005287:Ferredoxin-NADP Reductase; D009584:Nitrogen