Transcriptional analysis of the isiAB operon in salt-stressed cells of the cyanobacterium Synechocystis sp. PCC 6803.
Expression of the isiA and isiB genes was analysed in the cyanobacterium Synechocystis sp. PCC 6803 grown in high salt or in iron-deficient medium. The detection of a 2.3-knt transcript in Northern blot experiments indicated cotranscription of isiAB in an operon, which was confirmed by reverse transcriptase PCR. The abundance of a monocistronic 1.25-knt isiA-specific mRNA was about 10-fold higher than the dicistronic message. The isiAB-specific transcripts were most abundant in cells adapted to 342 mM NaCl and under iron deficiency. The promoter of the operon was mapped to 211 bp upstream of the translational start. A putative Fur binding site was detected immediately upstream of the GTG start codon. A preliminary transcript of about 0.2 knt was detected in cells grown in conditions in which the isiAB operon was not transcribed. This indicates that a repressor binds to the identified Fur binding site and thus inhibits isiAB transcription under low salt and iron replete conditions.
Vinnemeier
J
J
Universität Rostock, FB Biologie, Germany.
Kunert
A
A
Hagemann
M
M
D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics; D003470:Culture Media / Q000737:chemistry; D000458:Cyanobacteria / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D005418:Flavodoxin / Q000235:genetics; D005798:Genes, Bacterial; D045342:Light-Harvesting Protein Complexes; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012965:Sodium Chloride / Q000494:pharmacology; D014158:Transcription, Genetic / Q000235:genetics
D001426:Bacterial Proteins; D002352:Carrier Proteins; D003470:Culture Media; D005418:Flavodoxin; D045342:Light-Harvesting Protein Complexes; C076726:chlorophyll A binding protein CP43, Cyanobacteria; D012965:Sodium Chloride