The response of electron transport mediated by active NADPH dehydrogenase complexes to heat stress in the cyanobacterium Synechocystis 6803 |
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Authors: | WeiMin Ma LanZhen Wei QuanXi Wang |
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Affiliation: | (1) College of Life and Environment Sciences, Shanghai Normal University, Shanghai, 200234, China |
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Abstract: | The electron-transport machinery in photosynthetic membranes is known to be very sensitive to heat. In this study, the rate
of electron transport (ETR) driven by photosystem I (PSI) and photosystem II (PSII) during heat stress in the wild-type Synechocystis sp. strain PCC 6803 (WT) and its ndh gene inactivation mutants ΔndhB (M55) and ΔndhD1/ndhD2 (D1/D2) was simultaneously assessed by using the novel Dual-PAM-100 measuring system. The rate of electron transport driven
by the photosystems (ETRPSs) in the WT, M55, and D1/D2 cells incubated at 30°C and at 55°C for 10 min was compared. Incubation at 55°C for 10 min significantly
inhibited PSII-driven ETR (ETRPSII) in the WT, M55 and D1/D2 cells, and the extent of inhibition in both the M55 and D1/D2 cells was greater than that in the
WT cells. Further, PSI-driven ETR (ETRPSI) was stimulated in both the WT and D1/D2 cells, and this rate was increased to a greater extent in the D1/D2 than in the
WT cells. However, ETRPSI was considerably inhibited in the M55 cells. Analysis of the effect of heat stress on ETRPSs with regard to the alterations in the 2 active NDH-1 complexes in the WT, M55, and D1/D2 cells indicated that the active
NDH-1 supercomplex and mediumcomplex are essential for alleviating the heat-induced inhibition of ETRPSII and for accelerating the heat-induced stimulation of ETRPSI, respectively. Further, it is believed that these effects are most likely brought about by the electron transport mediated
by each of these 2 active NDH-1 complexes.
Supported by the National Natural Science Foundation of China (Grant No. 30770175), the Natural Science Foundation of Shanghai
Muncipality (Grant No. 07ZR14086), the Innovation Program of Shanghai Municipal Education Commission (Grant No. 08ZZ67), the
Key Foundation Project of Shanghai (Grant No. 06JC14091), and the Leading Academic Discipline Project of Shanghai Municipal
Education Commission (Grant No. J50401) |
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Keywords: | active NDH-1 complexes heat response photosystems-driven electron transport Synechocystis 6803 |
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