Translocation of alpha-sarcin across the lipid bilayer of asolectin vesicles

• Published in: Biochemical journal Vol. 295; no. 1; pp. 221 - 225
• Main Authors: Onaderra, M, Mancheno, J.M, Gasset, M, Lacadena, J, Schiavo, G, Martinez del Pozo, A, Gavilanes, J.G
• Format: Journal Article
• Language: English
• Published: Colchester Portland Press 01.10.1993
• Subjects: Analytical, structural and metabolic biochemistry; Antineoplastic Agents - metabolism; Aspergillus; Biological and medical sciences; Biological Transport; Endoribonucleases; Fundamental and applied biological sciences. Psychology; Fungal Proteins - metabolism; Fungal Proteins - radiation effects; Glycine max; Light; Lipid Bilayers - metabolism; liposomes; Liposomes - metabolism; membranes; Miscellaneous; Molecular Probes; mycotoxins; Phosphatidylcholines; Phospholipids - metabolism; Protein Synthesis Inhibitors - metabolism; Proteins; RNA, Transfer - metabolism; transport processes; Trypsin - metabolism; Encapsulation; Membrane protein; Serine endopeptidases; tRNA; Enzyme; Liposome; Phospholipid; Artificial membrane; Membrane translocation; Fungi; Trypsin; Aspergillus giganteus; Phosphatidylcholine; Hydrolases; Models; Fungi Imperfecti; Proteinases; Thallophyta
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2950221

alpha-Sarcin is a cytotoxic protein produced by the mould Aspergillus giganteus. Insertion of alpha-sarcin into asolectin membranes has been demonstrated by protein labelling with photoreactive phospholipids. alpha-Sarcin added externally to tRNA-containing asolectin liposomes degrades the entrapped tRNA. Trypsin-containing asolectin liposomes were also prepared. Encapsulated trypsin degrades alpha-sarcin, even in the presence of a large excess of external hen egg-white trypsin inhibitor to prevent any alpha-sarcin degradation outside the vesicles. These processes occur only with acidic phospholipids and were not observed when phosphatidylcholine vesicles were used. These results indicate that alpha-sarcin penetrates the lipid bilayer and becomes exposed to the lumen of negatively charged liposomes.