The effects of spermine and spermidine on the structure of photosystem II proteins in relation to inhibition of electron transport

Abstract

Polyamines (PAs) are ubiquitous in cells of higher plants and play an important role in many biological functions. Because PAs affect photosynthetic oxygen evolution, this study is designed to investigate the interaction of spermine (Spm) and spermidine (Spd) cations with proteins of photosystem II (PSII) using PSII-enriched submembranes fraction with polyamine concentrations of 0.01-10 mM. Fourier transform infrared (FTIR) difference spectroscopy with its self-deconvolution and second derivative resolution enhancement as well as curve-fitting procedures was applied, in order to determine the cation binding mode, the protein conformational changes and the structural properties of cation-protein complexes. It is shown that at low polyamine concentration, cation-protein interaction (H-bonding) is through the polypeptide C=O groups with no major perturbation of the protein secondary structure. As cation concentration increases, the polyamine complexation causes significant alterations of the protein secondary structure with a decrease of the alpha-helical domains from 47% (uncomplexed PSII) up to 37% (cation complexes) and an increase in the beta-sheet structure from 18% (uncomplexed PSII) up to 29% (cation complexes). Correlations between the effects of polyamines on protein secondary structure and on the rate of oxygen evolution in PSII are also established.

A Review: Polyamines and Photosynthesis

“…However, high concentration of polyamines added to submembrane fractions of photosynthetic apparatus causes a strong inhibition of PSII activity (Hamdani et al, 2010). FTIR spectroscopy analysis Spd and Spm at higher cation concentrations (5 and 10 mM), the result showed that the polyamine significant alterations of the thylakoid protein secondary structure with a decrease of the -helical domains from 47% (uncomplexed PSII) up to 37% (cation complexes) and an increase in the -sheet structure from 18% up to 29% (Bograh et al, 1997). So far, this specific inhibition mechanism of polyamines is not clear, but it is likely that the proteins were affected by these polycations re either extrinsic polypeptides associated with the oxygen evolving complex or portions of integral polypeptides protruding at the surface of the PSII membranes (Beauchemin et al, 2007).…”

Supramolecular Fmoc-valyl based nanoassemblies for delivery of mitoxantrone into HeLa cells

“…Previous work has shown that the amide I peak of pure spermidine appears at 1623 cm -1 and amide II peaks are seen at 1550 cm -1 , 1575 cm -1 [49][50]. We attribute the shifts observed in the case of the construct to the presence of boc groups as well as conjugation with Fmoc-Val.…”

The Effect of Cholesterol on the Solution Structure of Proteins of Photosystem II. Protein Secondary Structure and Photosynthetic Oxygen Evolution

“…Such generated spectral differences are used in order to analyze the nature of a chol-PSII interaction, in regard to different binding modes (such as protein C AO and C ON as well as chol-lipid complexation). The detailed spectral manipulations and data treatments were given in our recent publication (10). The spectra presented here are not smoothed.…”

“…The observed spectral differences are mainly due to the minor interaction of chol with the protein CAO and CON groups as well as with the lipid carbonyl donor atom. As chol concentration increased (1,5,10, and 20 mM), the negative features at 1658 (amide I), 1548 (amide II), and 1738 cm Ϫ1 (lipid carbonyl) gained intensity in the difference spectra of the chol-PSII complexes (Fig. 1).…”