Photosynthetic energy storage efficiency in Chlamydomonas reinhardtii, based on microsecond photoacoustics

Chengyi Yan; Oscar Schofield; Zvy Dubinsky; David Mauzerall; Paul G. Falkowski; Maxim Y. Gorbunov

doi:10.1007/s11120-011-9682-9

Photosynthetic energy storage efficiency in Chlamydomonas reinhardtii, based on microsecond photoacoustics

Chengyi Yan, Oscar Schofield, Zvy Dubinsky, David Mauzerall, Paul G. Falkowski, Maxim Y. Gorbunov

Department of Geography

Research output: Contribution to journal › Article › peer-review

3 Scopus citations

Abstract

Using a novel, pulsed micro-second time-resolved photoacoustic (PA) instrument, we measured thermal dissipation and energy storage (ES) in the intact cells of wild type (WT) Chlamydomonas reinhardtii, and mutants lacking either PSI or PSII reaction centers (RCs). On this time scale, the kinetic contributions of the thermal expansion component due to heat dissipation of absorbed energy and the negative volume change due to electrostriction induced by charge separation in each of the photosystems could be readily distinguished. Kinetic analysis revealed that PSI and PSII RCs exhibit strikingly different PA signals where PSI is characterized by a strong electrostriction signal and a weak thermal expansion component while PSII has a small electrostriction component and large thermal expansion. The calculated ES efficiencies at ~10 μs were estimated to be 80 ± 5 and 50 ± 13% for PSII-deficient mutants and PSI-deficient mutants, respectively, and 67 ± 2% for WT. The overall ES efficiency was positively correlated with the ratio of PSI to PSI + PSII. Our results suggest that the shallow excitonic trap in PSII limits the efficiency of ES as a result of an evolutionary frozen metabolic framework of two photosystems in all oxygenic photoautotrophs.

Original language	English
Pages (from-to)	215-224
Number of pages	10
Journal	Photosynthesis Research
Volume	108
Issue number	2-3
DOIs	https://doi.org/10.1007/s11120-011-9682-9
State	Published - Sep 2011

Bibliographical note

Funding Information:
Acknowledgments This study was supported by the US Department of Defense via Strategic Environmental Research and Development Program, NASA, and US-Israel Bi-national Science Foundation, and Rutgers Graduate Fellowship (to CY). We appreciate two anonymous reviewers for their constructive comments.

Keywords

Chlamydomonas reinhardtii
Energy storage efficiency
Photoacoustics
Photosystem I
Photosystem II

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title = "Photosynthetic energy storage efficiency in Chlamydomonas reinhardtii, based on microsecond photoacoustics",

abstract = "Using a novel, pulsed micro-second time-resolved photoacoustic (PA) instrument, we measured thermal dissipation and energy storage (ES) in the intact cells of wild type (WT) Chlamydomonas reinhardtii, and mutants lacking either PSI or PSII reaction centers (RCs). On this time scale, the kinetic contributions of the thermal expansion component due to heat dissipation of absorbed energy and the negative volume change due to electrostriction induced by charge separation in each of the photosystems could be readily distinguished. Kinetic analysis revealed that PSI and PSII RCs exhibit strikingly different PA signals where PSI is characterized by a strong electrostriction signal and a weak thermal expansion component while PSII has a small electrostriction component and large thermal expansion. The calculated ES efficiencies at ~10 μs were estimated to be 80 ± 5 and 50 ± 13% for PSII-deficient mutants and PSI-deficient mutants, respectively, and 67 ± 2% for WT. The overall ES efficiency was positively correlated with the ratio of PSI to PSI + PSII. Our results suggest that the shallow excitonic trap in PSII limits the efficiency of ES as a result of an evolutionary frozen metabolic framework of two photosystems in all oxygenic photoautotrophs.",

keywords = "Chlamydomonas reinhardtii, Energy storage efficiency, Photoacoustics, Photosystem I, Photosystem II",

author = "Chengyi Yan and Oscar Schofield and Zvy Dubinsky and David Mauzerall and Falkowski, {Paul G.} and Gorbunov, {Maxim Y.}",

note = "Funding Information: Acknowledgments This study was supported by the US Department of Defense via Strategic Environmental Research and Development Program, NASA, and US-Israel Bi-national Science Foundation, and Rutgers Graduate Fellowship (to CY). We appreciate two anonymous reviewers for their constructive comments.",

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AU - Yan, Chengyi

AU - Schofield, Oscar

AU - Dubinsky, Zvy

AU - Mauzerall, David

AU - Falkowski, Paul G.

AU - Gorbunov, Maxim Y.

N1 - Funding Information: Acknowledgments This study was supported by the US Department of Defense via Strategic Environmental Research and Development Program, NASA, and US-Israel Bi-national Science Foundation, and Rutgers Graduate Fellowship (to CY). We appreciate two anonymous reviewers for their constructive comments.

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N2 - Using a novel, pulsed micro-second time-resolved photoacoustic (PA) instrument, we measured thermal dissipation and energy storage (ES) in the intact cells of wild type (WT) Chlamydomonas reinhardtii, and mutants lacking either PSI or PSII reaction centers (RCs). On this time scale, the kinetic contributions of the thermal expansion component due to heat dissipation of absorbed energy and the negative volume change due to electrostriction induced by charge separation in each of the photosystems could be readily distinguished. Kinetic analysis revealed that PSI and PSII RCs exhibit strikingly different PA signals where PSI is characterized by a strong electrostriction signal and a weak thermal expansion component while PSII has a small electrostriction component and large thermal expansion. The calculated ES efficiencies at ~10 μs were estimated to be 80 ± 5 and 50 ± 13% for PSII-deficient mutants and PSI-deficient mutants, respectively, and 67 ± 2% for WT. The overall ES efficiency was positively correlated with the ratio of PSI to PSI + PSII. Our results suggest that the shallow excitonic trap in PSII limits the efficiency of ES as a result of an evolutionary frozen metabolic framework of two photosystems in all oxygenic photoautotrophs.

AB - Using a novel, pulsed micro-second time-resolved photoacoustic (PA) instrument, we measured thermal dissipation and energy storage (ES) in the intact cells of wild type (WT) Chlamydomonas reinhardtii, and mutants lacking either PSI or PSII reaction centers (RCs). On this time scale, the kinetic contributions of the thermal expansion component due to heat dissipation of absorbed energy and the negative volume change due to electrostriction induced by charge separation in each of the photosystems could be readily distinguished. Kinetic analysis revealed that PSI and PSII RCs exhibit strikingly different PA signals where PSI is characterized by a strong electrostriction signal and a weak thermal expansion component while PSII has a small electrostriction component and large thermal expansion. The calculated ES efficiencies at ~10 μs were estimated to be 80 ± 5 and 50 ± 13% for PSII-deficient mutants and PSI-deficient mutants, respectively, and 67 ± 2% for WT. The overall ES efficiency was positively correlated with the ratio of PSI to PSI + PSII. Our results suggest that the shallow excitonic trap in PSII limits the efficiency of ES as a result of an evolutionary frozen metabolic framework of two photosystems in all oxygenic photoautotrophs.

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Photosynthetic energy storage efficiency in Chlamydomonas reinhardtii, based on microsecond photoacoustics

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Keywords

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