title: The photosensitizing activity of haematoporphyrin on mollicutes.
abstract: The photosensitizing activity of haematoporphyrin (HP) on Mycoplasma hominis and Acholeplasma laidlawii was studied as a function of the phase of growth and the amount of sterols in the cell membrane. Less HP was bound to cells when the membrane had a high sterol content. Both strains in the exponential but not in the stationary phase of growth were sensitive to HP treatment (above 1 microgram ml-1) in the dark. Visible light irradiation of HP-loaded cells caused in all cases a decrease of cell survival, with concomitant changes in the pattern of membrane proteins that suggested protein-protein cross-linking, and the appearance of ultrastructural alterations (rounded and lysed cells); the photosensitivity was indirectly related to the sterol content of the cell membrane. On the whole, our findings suggest that the cell membrane is a major target for HP photosensitization of mycoplasma cells.
mesh_terms: D000128:Acholeplasma laidlawii / Q000187:drug effects* / Q000528:radiation effects; D002462:Cell Membrane / Q000032:analysis; D004591:Electrophoresis, Polyacrylamide Gel; D006415:Hematoporphyrins / Q000494:pharmacology*; D008027:Light; D008565:Membrane Proteins / Q000032:analysis; D009174:Mycoplasma / Q000187:drug effects* / Q000528:radiation effects; D013997:Time Factors
chemical_list: D006415:Hematoporphyrins; D008565:Membrane Proteins