Nitrogen status modulates the expression of RNA-binding proteins in cyanobacteria.
Biochemical responses to cold and osmotic stresses overlap because each decreases the availability of free water. Since RNA-binding proteins are known to accumulate following cold stress and play key roles in regulating transcription termination, the effect of osmotic stress on expression of RNA-binding proteins was examined. The transcript levels of four genes encoding RNA-binding proteins (rbpA, rbpB, rbpC and rbpD) were monitored in Anabaena sp. PCC 7120 cultures supplemented with ammonium ions or growing under nitrogen-fixing conditions. Steady-state transcript levels of all four genes increased transiently in response to a temperature shift from 30 to 20 degrees C under both nitrogen regimes. Osmotic stress also enhanced rbpB, rbpC and rbpD gene expression in ammonium grown cultures. In the absence of a combined nitrogen source, osmotic stress repressed the short-term induction of rbp gene expression. The accumulation of RNA-binding proteins did not follow transcript levels, but remained high 24 h after stress initiation. It is concluded that nitrogen nutrition modulates the stress-responsive regulation of RNA-binding proteins in cyanobacteria, providing a potential mechanism to integrate environmental and developmental signals.
Department of Pediatrics, Box 088, MD Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA. smori@mdacc.tmc.edu
Shahram
S
Mori
Adam
A
Castoreno
Martin E
ME
Mulligan
Peter J
PJ
Lammers
D017033:Anabaena / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D003080:Cold Temperature; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D009584:Nitrogen / Q000378:metabolism / Q000494:pharmacology*; D009997:Osmotic Pressure; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects*
D016601:RNA-Binding Proteins; D009584:Nitrogen