Phytohemagglutinin and Light-induced Charge Density Effects On Plasma Membrane of Plectonemaboryanum - Phytohemagglutinin and Light-induced Charge Density Effects On Plasma Membrane of Plectonemaboryanum - Open Access Pub

Effects of the plant lectin phytohemagglutinin M (PHA-M) and illumination on the electrophoretic mobility (EPM) and 90°-light scattering of suspension of spheroplasts obtained by lysis of the unicellular diazothrophic cyanobacteriumPlectonemaboryanumwere studied. Cells cultures were grown on media with different iron content: an iron-deficient (denominated as “Fe-starved” culture), an iron-sufficient (“Fe-sufficient”), and a twentyfold iron excess medium (“Fe-excess”). Lectin addition led to a decrease of the membrane charge density and aggregation of the vesicles. Our results indicate significant influence of the Fe2+ and illumination on the lectin-induced decreasing of EPM and light scattering intensity. DOI10.14302/issn.2377-2549.jndc-13-262 The electric charge distributed on the surface of biological membranes plays an important role in the regulation of the molecular membrane processes, but also in the processes of interaction of biological cells with chemical substances. Deprivation of micronutrients can profoundly affect photosynthetic electron transfer 1. Iron (Fe), manganese (Mn), magnesium (Mg) and copper (Cu) are essential cofactors for the operation of the oxygenic photosynthetic electron transfer apparatus2. Although abundant in the earth’s crust, Fe predominates in insoluble Fe (III) precipitates and is largely unavailable to plants, especially at neutral or alkaline pH. As most biological membranes, spheroplasts isolated in vitro as closed vesicles are negatively charged at neutral pH. Investigation of the nature of the surface charges is important in order to obtain information about the surface components and the aggregation processes of the spheroplasts vesicles. Using the Gouy-Chapman theory3, 4,we investigated the influence of chemical modification of negative charges on the thylakoid membranes and found that they facilitate the entropy-driven ‘depletion attraction’ between the adjacent membranes. The widespread distribution of lectins throughout the plant kingdom and their abundance in many plants suggest that these molecules are of physiological importance5. Lectin receptors are the kind of protein macromolecules playing a role of specific determinants of cell-cell recognition. The characteristic property of lectins is their ability of binding to specific carbohydrate structure and to provide by that a basis of biologically reliable recognition6. Due to their multivalent binding character the lectins, when added exogenously, cause crosslink and molecular reorganizations in the cell membrane bilayer7. Phytohemagglutinin (lectin of