A1 Refereed original research article in a scientific journal
Acclimation to High CO2 Requires the omega Subunit of the RNA Polymerase in Synechocystis
Authors: Juha Kurkela, Kaisa Hakkila, Taras Antal, Taina Tyystjärvi
Publisher: AMER SOC PLANT BIOLOGISTS
Publication year: 2017
Journal: Plant Physiology
Journal name in source: PLANT PHYSIOLOGY
Journal acronym: PLANT PHYSIOL
Volume: 174
Issue: 1
First page : 172
Last page: 184
Number of pages: 13
ISSN: 0032-0889
eISSN: 1532-2548
DOI: https://doi.org/10.1104/pp.16.01953
Abstract
Inactivation of the nonessential omega-subunit of the RNA polymerase core in the Delta rpoZ strain of the model cyanobacterium Synechocystis sp. PCC 6803 leads to a unique high-CO2-sensitive phenotype. Supplementing air in the growth chamber with 30 mL L-1 (3%) CO2 accelerated the growth rate of the control strain (CS) 4-fold, whereas Delta rpoZ did not grow faster than under ambient air. The slow growth of Delta rpoZ during the first days in high CO2 was due to the inability of the mutant cells to adjust photosynthesis to high CO2. The light-saturated photosynthetic activity of Delta rpoZ in high CO2 was only half of that measured in CS, Rubisco content was one-third lower, and cells of Delta rpoZ were not able to increase light-harvesting phycobilisome antenna like CS upon high-CO2 treatment. In addition, altered structural and functional organization of photosystem I and photosystem II were detected in the Delta rpoZ strain compared with CS when cells were grown in high CO2 but not in ambient air. Moreover, respiration of Delta rpoZ did not acclimate to high CO2. Unlike the photosynthetic complexes, the RNA polymerase complex and ribosomes were produced in high CO2 similarly as in CS. Our results indicate that the deletion of the v-subunit specifically affects photosynthesis and respiration, but transcription and translation remain active. Thus, the specific effect of the omega-subunit on photosynthesis but not on all household processes suggests that the omega-subunit might have a regulatory function in cyanobacteria.
Inactivation of the nonessential omega-subunit of the RNA polymerase core in the Delta rpoZ strain of the model cyanobacterium Synechocystis sp. PCC 6803 leads to a unique high-CO2-sensitive phenotype. Supplementing air in the growth chamber with 30 mL L-1 (3%) CO2 accelerated the growth rate of the control strain (CS) 4-fold, whereas Delta rpoZ did not grow faster than under ambient air. The slow growth of Delta rpoZ during the first days in high CO2 was due to the inability of the mutant cells to adjust photosynthesis to high CO2. The light-saturated photosynthetic activity of Delta rpoZ in high CO2 was only half of that measured in CS, Rubisco content was one-third lower, and cells of Delta rpoZ were not able to increase light-harvesting phycobilisome antenna like CS upon high-CO2 treatment. In addition, altered structural and functional organization of photosystem I and photosystem II were detected in the Delta rpoZ strain compared with CS when cells were grown in high CO2 but not in ambient air. Moreover, respiration of Delta rpoZ did not acclimate to high CO2. Unlike the photosynthetic complexes, the RNA polymerase complex and ribosomes were produced in high CO2 similarly as in CS. Our results indicate that the deletion of the v-subunit specifically affects photosynthesis and respiration, but transcription and translation remain active. Thus, the specific effect of the omega-subunit on photosynthesis but not on all household processes suggests that the omega-subunit might have a regulatory function in cyanobacteria.
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