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Arginine Decarboxylase Is Localized in Chloroplasts
A. Borrell1, F. A. Culianez-Macia, T. Altabella
1Laboratori de Fisiologia Vegetal, Facultat de Farmacia, Universitat de Barcelona, Diagonal 643, 08028 Barcelona, Spain (A.B., T.A., D.F., A.F.T.).
Plant Physiology
|November 1, 1995
Summary
Plants use arginine decarboxylase (ADC) to produce putrescine, a polyamine precursor. This study locates ADC in chloroplasts, offering evolutionary insights into plant polyamine biosynthesis and its distinction from animals.
Area of Science:
- Plant biochemistry
- Molecular biology
- Evolutionary biology
Background:
- Plants synthesize the polyamine precursor putrescine via ornithine decarboxylase or arginine decarboxylase (ADC).
- The precise cellular and subcellular localization of these enzymes has hindered understanding of polyamine roles in plants.
Purpose of the Study:
- To investigate the spatial distribution and subcellular localization of ADC protein in oat (Avena sativa L.) tissues.
- To correlate ADC levels with activity and putrescine production under osmotic stress.
Main Methods:
- Generation of polyclonal antibodies against oat ADC.
- Immunoblotting and immunocytochemistry for protein localization.
- Cell fractionation to determine subcellular location.
- Enzyme activity assays and putrescine quantification.
Main Results:
- ADC exhibits organ-specific distribution in oat tissues.
- ADC protein is localized within chloroplasts, associated with the thylakoid membrane.
- Increased ADC protein levels correlate with enhanced ADC activity and putrescine accumulation in osmotically stressed leaves.
Conclusions:
- A model for compartmentalization of the arginine pathway and putrescine biosynthesis in photosynthetic tissues is proposed.
- Chloroplast localization of ADC provides evolutionary context for dual polyamine pathways in plants and absence in animals.