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Aging of Dry Desiccation-Tolerant Pollen Does Not Affect Protein Secondary Structure
W. F. Wolkers1, F. A. Hoekstra
1Department of Plant Physiology, Wageningen Agricultural University, Arboretumlaan 4, NL-6703 BD Wageningen, The Netherlands.
Plant Physiology
|November 1, 1995
Summary
Aging Typha latifolia pollen shows decreased membrane fluidity but not large-scale protein aggregation. Fourier transform infrared microspectroscopy (FTIR) revealed conserved protein secondary structures, highlighting FTIR
Area of Science:
- Plant biology
- Biophysics
- Spectroscopy
Background:
- Membrane phase behavior and protein structure are critical for pollen viability.
- Aging in pollen can lead to changes in membrane fluidity and protein conformation.
- Understanding these changes is essential for plant reproduction and conservation.
Purpose of the Study:
- To investigate the impact of aging on protein secondary structure and membrane phase behavior in Typha latifolia pollen.
- To assess the role of Fourier transform infrared microspectroscopy (FTIR) in studying these changes in intact plant cells.
Main Methods:
- Fourier transform infrared microspectroscopy (FTIR) was employed to analyze protein secondary structure and membrane properties.
- Curve-fitting analysis of infrared absorbance spectra (amide-1 bands) was used to quantify protein structures.
- In situ FTIR and heat-denaturing experiments were conducted on fresh and aged pollen, including isolated cytoplasmic proteins.
Main Results:
- Aging Typha latifolia pollen exhibited significantly decreased membrane fluidity, shifting from a liquid crystalline phase.
- Despite reduced fluidity, large-scale irreversible protein aggregation was not observed in aged pollen membranes.
- FTIR analysis revealed a high proportion of [alpha]-helical structures (48%) in membrane proteins and conserved secondary structures in cytoplasmic proteins.
- Heat-denaturing experiments indicated the potential for irreversible protein aggregation under stress.
Conclusions:
- FTIR is a highly effective technique for studying protein secondary structure in plant cells across different hydration levels and developmental stages.
- Aging affects pollen membrane fluidity but does not necessarily lead to widespread protein aggregation.
- Protein secondary structure, particularly [alpha]-helical content, remains relatively stable in Typha latifolia pollen during aging and dehydration.
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