Present address: Botanisches Intitut der Universität zu Köln, Gyrhofstrasse 15, 50931 Köln, Germany.
Analysis of cytosolic and plastidic serine acetyltransferase mutants and subcellular metabolite distributions suggests interplay of the cellular compartments for cysteine biosynthesis in Arabidopsis
Article first published online: 6 FEB 2009
© 2009 Blackwell Publishing Ltd
Plant, Cell & Environment
Volume 32, Issue 4, pages 349–367, April 2009
How to Cite
KRUEGER, S., NIEHL, A., LOPEZ MARTIN, M. C., STEINHAUSER, D., DONATH, A., HILDEBRANDT, T., ROMERO, L. C., HOEFGEN, R., GOTOR, C. and HESSE, H. (2009), Analysis of cytosolic and plastidic serine acetyltransferase mutants and subcellular metabolite distributions suggests interplay of the cellular compartments for cysteine biosynthesis in Arabidopsis. Plant, Cell & Environment, 32: 349–367. doi: 10.1111/j.1365-3040.2009.01928.x
- Issue published online: 5 MAR 2009
- Article first published online: 6 FEB 2009
- Received 17 September 2008; received in revised form 1 December 2008; accepted for publication 2 December 2008
- non-aqueous fractionation;
- sulphur metabolism
In plants, the enzymes for cysteine synthesis serine acetyltransferase (SAT) and O-acetylserine-(thiol)-lyase (OASTL) are present in the cytosol, plastids and mitochondria. However, it is still not clearly resolved to what extent the different compartments are involved in cysteine biosynthesis and how compartmentation influences the regulation of this biosynthetic pathway. To address these questions, we analysed Arabidopsis thaliana T-DNA insertion mutants for cytosolic and plastidic SAT isoforms. In addition, the subcellular distribution of enzyme activities and metabolite concentrations implicated in cysteine and glutathione biosynthesis were revealed by non-aqueous fractionation (NAF). We demonstrate that cytosolic SERAT1.1 and plastidic SERAT2.1 do not contribute to cysteine biosynthesis to a major extent, but may function to overcome transport limitations of O-acetylserine (OAS) from mitochondria. Substantiated by predominantly cytosolic cysteine pools, considerable amounts of sulphide and presence of OAS in the cytosol, our results suggest that the cytosol is the principal site for cysteine biosynthesis. Subcellular metabolite analysis further indicated efficient transport of cysteine, γ-glutamylcysteine and glutathione between the compartments. With respect to regulation of cysteine biosynthesis, estimation of subcellular OAS and sulphide concentrations established that OAS is limiting for cysteine biosynthesis and that SAT is mainly present bound in the cysteine–synthase complex.