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Polyamine binding to proteins in oat and Petunia protoplasts
Y Mizrahi1, P B Applewhite, A W Galston
1Department of Biology, Yale University, New Haven, Connecticut 06511, USA.
Plant Physiology
|January 1, 1989
Summary
Spermidine (Spd) binds to proteins in plants like Petunia, but is converted to 1,3-diaminopropane (DAP) in oats. This DAP-protein complex in oats has covalent attachment and its isolation depends on specific extraction conditions.
Area of Science:
- Plant biochemistry
- Molecular biology
- Polyamine metabolism
Background:
- Previous studies showed spermidine (Spd) binding to a specific protein in tobacco.
- The general importance of Spd-protein complexes across plant species was not well understood.
Purpose of the Study:
- To investigate the general occurrence and characteristics of Spd-protein complexes in different plant species.
- To isolate and characterize Spd-protein complexes from Petunia and oat protoplasts.
Main Methods:
- Protoplast isolation from Petunia and oat (Avena sativa) leaf tissues.
- Radioactive labeling and extraction of polyamine-protein complexes.
- Biochemical analysis including protein precipitation, column fractionation (Sephacryl), and enzymatic treatments (Pronase, DNAse, RNAse).
Main Results:
- In Petunia, radioactive Spd bound to proteins, similar to tobacco.
- In oat, Spd was converted to 1,3-diaminopropane (DAP) by polyamine oxidase before binding to proteins.
- DAP-protein complex formation in oat was influenced by leaf age, light, and temperature.
- Optimal extraction of the oat DAP-protein complex required a pH 8.8 carbonate buffer with SDS.
- The oat DAP-protein complex molecular size exceeded 45 kDa and showed covalent attachment to protein, released by Pronase.
Conclusions:
- Spd-protein interactions are not universal; metabolic conversion to DAP occurs in some species like oat.
- The formation and extraction of DAP-protein complexes are condition-dependent.
- The binding of DAP to proteins in oat appears to be covalent, suggesting a significant post-translational modification or interaction.
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