Glyceraldehyde-3-phosphate dehydrogenase subunits A and B are essential to maintain photosynthetic efficiency
Abstract In plants, glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.12) reversibly converts 1,3-bisphosphoglycerate to glyceraldehyde-3-phosphate coupled with the reduction of NADPH to NADP+. The GAPDH enzyme that functions in the Calvin–Benson cycle is assembled either from 4 glyceraldehy...
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Published in | Plant physiology (Bethesda) Vol. 192; no. 4; pp. 2989 - 3000 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
US
Oxford University Press
03.08.2023
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Subjects | |
Online Access | Get full text |
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Summary: | Abstract
In plants, glyceraldehyde-3-phosphate dehydrogenase (GAPDH; EC 1.2.1.12) reversibly converts 1,3-bisphosphoglycerate to glyceraldehyde-3-phosphate coupled with the reduction of NADPH to NADP+. The GAPDH enzyme that functions in the Calvin–Benson cycle is assembled either from 4 glyceraldehyde-3-phosphate dehydrogenase A (GAPA) subunit proteins forming a homotetramer (A4) or from 2 GAPA and 2 glyceraldehyde-3-phosphate dehydrogenase B (GAPB) subunit proteins forming a heterotetramer (A2B2). The relative importance of these 2 forms of GAPDH in determining the rate of photosynthesis is unknown. To address this question, we measured the photosynthetic rates of Arabidopsis (Arabidopsis thaliana) plants containing reduced amounts of the GAPDH A and B subunits individually and jointly, using T-DNA insertion lines of GAPA and GAPB and transgenic GAPA and GAPB plants with reduced levels of these proteins. Here, we show that decreasing the levels of either the A or B subunits decreased the maximum efficiency of CO2 fixation, plant growth, and final biomass. Finally, these data showed that the reduction in GAPA protein to 9% wild-type levels resulted in a 73% decrease in carbon assimilation rates. In contrast, eliminating GAPB protein resulted in a 40% reduction in assimilation rates. This work demonstrates that the GAPA homotetramer can compensate for the loss of GAPB, whereas GAPB alone cannot compensate fully for the loss of the GAPA subunit. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 These authors contributed equally. The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (https://academic.oup.com/plphys/pages/General-Instructions) is: Andrew J Simkin (a.simkin@kent.ac.uk). Conflict of interest statement. The authors declare no conflict of interest. |
ISSN: | 0032-0889 1532-2548 |
DOI: | 10.1093/plphys/kiad256 |