SigC sigma factor is involved in acclimation to low inorganic carbon at high temperature in Synechocystis sp. PCC 6803.
Inactivation of the sigC gene (sll0184), encoding the group 2 sigma factor SigC, leads to a heat-sensitive phenotype of Synechocystis sp. PCC 6803. Cells of the DeltasigC strain grew poorly at 43 degrees C at pH 7.5 under ambient CO(2) conditions. Addition of inorganic carbon in the form of 3 % CO(2) or use of an alkaline growth medium (pH 8.3) restored the growth of the DeltasigC strain at 43 degrees C. These treatments compensate for the low concentration of inorganic carbon at high temperature. However, addition of organic carbon as glucose, pyruvate, succinate or 2-oxoglutarate did not restore growth of the DeltasigC strain at 43 degrees C. In the control strain, the amount of the SigC factor diminished after prolonged incubation at 43 degrees C if the pH of the growth medium was 7.5 or 6.7. Under alkaline conditions, the amount of the SigC factor remained constant at 43 degrees C and cells of the control strain grew better than at pH 7.5 or pH 6.7. The pH dependence of high-temperature growth was associated with changes in photosynthetic activity, indicating that the SigC factor is involved in adjustment of photosynthesis according to the amount of available inorganic carbon. Our results indicate that acclimation to low inorganic carbon is a part of acclimation to prolonged high temperature and that the SigC factor has a central role in this acclimation.
Gunnelius
Liisa
L
Plant Physiology and Molecular Biology, Department of Biology, University of Turku, FI-20014 Turku, Finland.
Tuominen
Ilona
I
Plant Physiology and Molecular Biology, Department of Biology, University of Turku, FI-20014 Turku, Finland.
Rantamäki
Susanne
S
Plant Physiology and Molecular Biology, Department of Biology, University of Turku, FI-20014 Turku, Finland.
Pollari
Maija
M
Plant Physiology and Molecular Biology, Department of Biology, University of Turku, FI-20014 Turku, Finland.
Ruotsalainen
Virpi
V
Plant Physiology and Molecular Biology, Department of Biology, University of Turku, FI-20014 Turku, Finland.
Tyystjärvi
Esa
E
Plant Physiology and Molecular Biology, Department of Biology, University of Turku, FI-20014 Turku, Finland.
Tyystjärvi
Taina
T
Plant Physiology and Molecular Biology, Department of Biology, University of Turku, FI-20014 Turku, Finland.
D000064:Acclimatization; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D003470:Culture Media; D000242:Cyclic AMP / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D010788:Photosynthesis; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism*; D046939:Synechocystis / Q000235:genetics / Q000254:growth & development*
D001426:Bacterial Proteins; D003470:Culture Media; D004268:DNA-Binding Proteins; D012808:Sigma Factor; C081467:sigC protein, Bacteria; D002245:Carbon Dioxide; D002244:Carbon; D000242:Cyclic AMP