The pH-dependent interaction of cinnamomin with lipid membranes investigated by fluorescence methods.
Cinnamomin, a new type II ribosome-inactivating protein (RIP), was found to be able to induce the release of calcein loaded in lecithin small unilamellar vesicles and the fusion or aggregation of the lecithin liposomes. Such induction could be promoted severalfold by a pH 5.0 environment, a condition similar to that in endocytic vesicles. Lowering the pH from 7.5 to 5.0 evoked conformational changes of cinnamomin and unmasked its hydrophobic areas, including the exposure of 1-anilino-8-naphthalenesulfonate (1,8-ANS) binding sites of the molecule. Some tryptophan residues with affinity to acrylamide were demonstrated to participate in the lipid-protein interaction. The pH dependent fusogenicity of type II RIP might suggest its in vivo function as a fusogen to exert its cytotoxicity.
Hu
R G
RG
Shanghai Institute of Biochemistry, Academia Sinica, P. R. China.
Tang
S
S
Liu
W Y
WY
D020418:Algal Proteins; D000817:Anilino Naphthalenesulfonates / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008027:Light; D008563:Membrane Lipids / Q000737:chemistry*; D008567:Membranes, Artificial; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism; D054790:Ribosome Inactivating Proteins, Type 2; D012542:Scattering, Radiation; D013050:Spectrometry, Fluorescence
D020418:Algal Proteins; D000817:Anilino Naphthalenesulfonates; D008563:Membrane Lipids; D008567:Membranes, Artificial; D011506:Proteins; D054790:Ribosome Inactivating Proteins, Type 2; C061930:cinnamomin, Phytophthora cinnamomi; C027132:1-anilino-8-naphthalenesulfonate