Wingler, A., Walker, R.P., Chen, Z. and Leegood, R.C. (1999) Phosphoenolpyruvate Carboxykinase Is Involved in the Decarboxylation of Aspartate in the Bundle Sheath of Maize. Plant Physiology, 120 (2). pp. 539-546. ISSN 0032-0889
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Abstract
We recently showed that maize (Zea mays L.) leaves contain appreciable amounts of phosphoenolpyruvate carboxykinase (PEPCK; R.P. Walker, R.M. Acheson, L.I. Técsi, R.C. Leegood [1997] Aust J Plant Physiol 24: 459–468). In the present study, we investigated the role of PEPCK in C4 photosynthesis in maize. PEPCK activity and protein were enriched in extracts from bundle-sheath (BS) strands compared with whole-leaf extracts. Decarboxylation of [4-14C]aspartate (Asp) by BS strands was dependent on the presence of 2-oxoglutarate and Mn2+, was stimulated by ATP, was inhibited by the PEPCK-specific inhibitor 3-mercaptopicolinic acid, and was independent of illumination. The principal product of Asp metabolism was phosphoenolpyruvate, whereas pyruvate was a minor product. Decarboxylation of [4-14C]malate was stimulated severalfold by Asp and 3-phosphoglycerate, was only slightly reduced in the absence of Mn2+ or in the presence of 3-mercaptopicolinic acid, and was light dependent. Our data show that decarboxylation of Asp and malate in BS cells of maize occurs via two different pathways: Whereas malate is mainly decarboxylated by NADP-malic enzyme, decarboxylation of Asp is dependent on the activity of PEPCK.
| Item Type: | Article |
|---|---|
| Copyright, Publisher and Additional Information: | © 1999 American Society of Plant Physiologists |
| Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Biological Sciences (Sheffield) > Department of Animal and Plant Sciences (Sheffield) The University of Sheffield > University of Sheffield Research Centres and Institutes > Robert Hill Institute (Sheffield) |
| Depositing User: | Repository Officer |
| Date Deposited: | 12 Oct 2004 |
| Last Modified: | 08 Feb 2013 16:46 |
| Status: | Published |
| Refereed: | Yes |
| URI: | http://eprints.whiterose.ac.uk/id/eprint/138 |
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