Increased activity of only an individual non-regulated enzyme fructose-1,6-bisphosphate aldolase in <Emphasis Type="Italic">Anabaena</Emphasis> sp. strain PCC 7120 stimulates photosynthetic yield |
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Authors: | Weimin Ma Lanzhen Wei Zongjuan Long Liping Chen Quanxi Wang |
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Institution: | (1) College of Life and Environment Sciences, Shanghai Normal University, 200234 Shanghai, China |
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Abstract: | The goal of this study was to investigate the contribution of increased activity of individual non-regulated enzymes in the
Calvin cycle to improve photosynthetic yield. Two non-regulated enzymes, rice fructose-1,6-bisphosphate aldolase (FBA) and
spinach triosephosphate isomerase (TPI), were individually cloned and overexpressed in the cyanobacterium Anabaena sp. strain PCC 7120 cells. The enzyme activity and the photosynthetic yield, as reflected by the cell growth rate, photosynthetic
oxygen evolution and dry cellular weight, were measured and compared between the wild-type and transgenic cells harboring
either FBA or TPI. Though the activity of these two individual non-regulated enzymes was similarly increased in the corresponding
transgenic cells, the contributions of each enzyme on the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco),
reflected by the levels of Rubisco large subunit, and the photosynthetic yield were different. Transgenic cells, carrying
FBA, showed an evident increase in Rubisco amount and photosynthetic yield, while there was no increase in cells harboring
TPI. This indicates that the contributions of non-regulated enzymes in the Calvin cycle on photosynthetic yield differed and
firstly reveals that increased activity of only a single non-regulated enzyme in transgenic cells markedly improves the photosynthetic
yield via stimulating the amount of Rubisco and consequently accelerating the ribulose-1,5-bisphosphate (RuBP) regeneration
rate. |
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Keywords: | Anabaena sp strain PCC 7120 Enzyme activity Fructose-1 6-bisphosphate aldolase Photosynthetic yield Triosephosphate isomerase |
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