ABSTRACT
Archaeon Aeropyrum pernix K1 is an obligate aerobic hyperthermophilic organism with C25,25-archeol membrane lipids with head groups containing inositol. Interactions of archaeosomes, liposomes prepared from lipids of A. pernix, with mammalian cells in vitro were studied. In vitro cytotoxicity was tested on five different cell lines: rodent mouse melanoma cells (B16-F1) and Chinese hamster ovary (CHO) cells, and three human cell lines-epithelial colorectal adenocarcinoma cells (CACO-2), liver hepatocellular carcinoma cell line (Hep G2) and endothelial umbilical vein cell line (EA.hy926). Archaeosomes were nontoxic to human Hep G2, CACO-2 and mildly toxic to rodent CHO and B16-F1 cells but showed strong cytotoxic effect on EA.hy926 cells. Confocal microscopy revealed that archaeosomes are taken up by endocytosis. The uptake of archaeosomes and the release of loaded calcein are more prominent in EA.hy926 cells, which is in line with high toxicity toward these cells. The mechanisms of uptake, release and action in these cells as well as in vivo functioning have to be further studied for possible targeted drug delivery.
Subject(s)
Aeropyrum/chemistry , Drug Carriers/toxicity , Endocytosis/drug effects , Lipids/chemistry , Aeropyrum/growth & development , Animals , Biomass , CHO Cells , Cell Culture Techniques , Cell Line, Tumor , Cell Survival/drug effects , Cricetinae , Cricetulus , Dose-Response Relationship, Drug , Drug Carriers/isolation & purification , Drug Carriers/metabolism , Endothelial Cells , Humans , Lipids/isolation & purification , Liposomes , Mice , Microscopy, Confocal , Microscopy, FluorescenceABSTRACT
An extremely halophilic haloarchaeon Sech7a, isolated from a solar saltern, was found to excrete halocin, a bacteriocin like substance. Optimal antimicrobial activity was obtained at 45 degrees C using 0.5% (w/v) glycerol and 0.5% (w/v) yeast extract as nutrients in SW media containing 3.4 M NaCl with pH value 7.5. Halocin Sech7a is a 10.7-kDa polypeptide, which is stable in a wide range of pH and is thermolabile at temperatures above 80 degrees C. As many other halophilic proteins, halocin Sech7a loses part of its activity upon exposure to low salt conditions, yet its activity can be restored after dialysis against initial saline conditions. Microscopic inspection revealed swelling and lysis of sensitive cells upon exposure to halocin Sech7a. These results indicate that haloarchaeon Sech7a excretes a novel bacteriocin.
