Limits...
The RUBISCO to Photosystem II Ratio Limits the Maximum Photosynthetic Rate in Picocyanobacteria.

Zorz JK, Allanach JR, Murphy CD, Roodvoets MS, Campbell DA, Cockshutt AM - Life (Basel) (2015)

Bottom Line: Marine Synechococcus and Prochlorococcus are picocyanobacteria predominating in subtropical, oligotrophic marine environments, a niche predicted to expand with climate change.When grown under common low light conditions Synechococcus WH 8102 and Prochlorococcus MED 4 show similar Cytochrome b6f and Photosystem I contents normalized to Photosystem II content, while Prochlorococcus MIT 9313 has twice the Cytochrome b6f content and four times the Photosystem I content of the other strains.Photosystem II electron transport capacity is highly correlated to the molar ratio of RUBISCO active sites to Photosystem II but not to the ratio of cytochrome b6f to Photosystem II, nor to the ratio of Photosystem I: Photosystem II.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G8, Canada. jkzorz@mta.ca.

ABSTRACT
Marine Synechococcus and Prochlorococcus are picocyanobacteria predominating in subtropical, oligotrophic marine environments, a niche predicted to expand with climate change. When grown under common low light conditions Synechococcus WH 8102 and Prochlorococcus MED 4 show similar Cytochrome b6f and Photosystem I contents normalized to Photosystem II content, while Prochlorococcus MIT 9313 has twice the Cytochrome b6f content and four times the Photosystem I content of the other strains. Interestingly, the Prochlorococcus strains contain only one third to one half of the RUBISCO catalytic subunits compared to the marine Synechococcus strain. The maximum Photosystem II electron transport rates were similar for the two Prochlorococcus strains but higher for the marine Synechococcus strain. Photosystem II electron transport capacity is highly correlated to the molar ratio of RUBISCO active sites to Photosystem II but not to the ratio of cytochrome b6f to Photosystem II, nor to the ratio of Photosystem I: Photosystem II. Thus, the catalytic capacity for the rate-limiting step of carbon fixation, the ultimate electron sink, appears to limit electron transport rates. The high abundance of Cytochrome b6f and Photosystem I in MIT 9313, combined with the slower flow of electrons away from Photosystem II and the relatively low level of RUBISCO, are consistent with cyclic electron flow around Photosystem I in this strain.

No MeSH data available.


Related in: MedlinePlus

Light response of PSII electron transport (e− PSII−1·s−1). Prochlorococcus MIT 9313: blue triangles; Prochlorococcus MED 4: green circles; Synechococcus WH8102: red squares. For clarity each plotted point represents the average of seven to eight independent determinations measured on separate cultures. The solid lines are hyperbolic tangent fits of the data; dotted lines show 95% confidence intervals on the regression.
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life-05-00403-f003: Light response of PSII electron transport (e− PSII−1·s−1). Prochlorococcus MIT 9313: blue triangles; Prochlorococcus MED 4: green circles; Synechococcus WH8102: red squares. For clarity each plotted point represents the average of seven to eight independent determinations measured on separate cultures. The solid lines are hyperbolic tangent fits of the data; dotted lines show 95% confidence intervals on the regression.

Mentions: Light response curves for PSII electron transport are shown in Figure 3. The two Prochlorococcus strains show very similar responses to increasing light, and show catalytic limitation of the electron transport rate by 150 μmol photons m−2·s−1. The marine Synechococcus strain is not catalytically limited over this irradiance range, as shown by its higher EK.


The RUBISCO to Photosystem II Ratio Limits the Maximum Photosynthetic Rate in Picocyanobacteria.

Zorz JK, Allanach JR, Murphy CD, Roodvoets MS, Campbell DA, Cockshutt AM - Life (Basel) (2015)

Light response of PSII electron transport (e− PSII−1·s−1). Prochlorococcus MIT 9313: blue triangles; Prochlorococcus MED 4: green circles; Synechococcus WH8102: red squares. For clarity each plotted point represents the average of seven to eight independent determinations measured on separate cultures. The solid lines are hyperbolic tangent fits of the data; dotted lines show 95% confidence intervals on the regression.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4390859&req=5

life-05-00403-f003: Light response of PSII electron transport (e− PSII−1·s−1). Prochlorococcus MIT 9313: blue triangles; Prochlorococcus MED 4: green circles; Synechococcus WH8102: red squares. For clarity each plotted point represents the average of seven to eight independent determinations measured on separate cultures. The solid lines are hyperbolic tangent fits of the data; dotted lines show 95% confidence intervals on the regression.
Mentions: Light response curves for PSII electron transport are shown in Figure 3. The two Prochlorococcus strains show very similar responses to increasing light, and show catalytic limitation of the electron transport rate by 150 μmol photons m−2·s−1. The marine Synechococcus strain is not catalytically limited over this irradiance range, as shown by its higher EK.

Bottom Line: Marine Synechococcus and Prochlorococcus are picocyanobacteria predominating in subtropical, oligotrophic marine environments, a niche predicted to expand with climate change.When grown under common low light conditions Synechococcus WH 8102 and Prochlorococcus MED 4 show similar Cytochrome b6f and Photosystem I contents normalized to Photosystem II content, while Prochlorococcus MIT 9313 has twice the Cytochrome b6f content and four times the Photosystem I content of the other strains.Photosystem II electron transport capacity is highly correlated to the molar ratio of RUBISCO active sites to Photosystem II but not to the ratio of cytochrome b6f to Photosystem II, nor to the ratio of Photosystem I: Photosystem II.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry & Biochemistry, Mount Allison University, Sackville, New Brunswick, E4L 1G8, Canada. jkzorz@mta.ca.

ABSTRACT
Marine Synechococcus and Prochlorococcus are picocyanobacteria predominating in subtropical, oligotrophic marine environments, a niche predicted to expand with climate change. When grown under common low light conditions Synechococcus WH 8102 and Prochlorococcus MED 4 show similar Cytochrome b6f and Photosystem I contents normalized to Photosystem II content, while Prochlorococcus MIT 9313 has twice the Cytochrome b6f content and four times the Photosystem I content of the other strains. Interestingly, the Prochlorococcus strains contain only one third to one half of the RUBISCO catalytic subunits compared to the marine Synechococcus strain. The maximum Photosystem II electron transport rates were similar for the two Prochlorococcus strains but higher for the marine Synechococcus strain. Photosystem II electron transport capacity is highly correlated to the molar ratio of RUBISCO active sites to Photosystem II but not to the ratio of cytochrome b6f to Photosystem II, nor to the ratio of Photosystem I: Photosystem II. Thus, the catalytic capacity for the rate-limiting step of carbon fixation, the ultimate electron sink, appears to limit electron transport rates. The high abundance of Cytochrome b6f and Photosystem I in MIT 9313, combined with the slower flow of electrons away from Photosystem II and the relatively low level of RUBISCO, are consistent with cyclic electron flow around Photosystem I in this strain.

No MeSH data available.


Related in: MedlinePlus