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Oxidative stress can affect in vitro GFP expression through its control of the gene silencing effect of the liposome prepared by 1,2-dioleoyl-3-trimethyl-ammonium propane (DOTAP). The gene silencing effect of cationic DOTAP liposome in in vitro GFP expression, especially focusing on its translation process, and the effects of oxidative stress on its silencing effect were investigated. GFP expression, initiated by mRNA, was found to be thoroughly inhibited in the presence of DOTAP liposome at concentration of more than 2.5 mM, though its inhibitory effect was reduced in the presence of hydrogen peroxide. The analyses of (i) the interaction of mRNA with DOTAP, (ii) the chemical structure of DOTAP, and (iii) the membrane fluidity of DOTAP liposome imply the possible role of gene expression by the liposome membrane and stress conditions.

The role of the charged liposome on the in vitro expression of green fluorescent protein (GFP) was investigated, focusing on its elemental steps such as transcription, translation and folding. The total GFP expression was enhanced to 145% when a neutral liposome (POPC: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocoline) was added externally to a cell-free translation system. On the contrary, the addition of the charged liposome composed of POPC with anionic 1-palmitoyl-2-oleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (POPG) or cationic stearyl amine (SA) inhibited the total GFP expression, depending on the surface charge density of liposome. In transcription, the RNA synthesis was enhanced regardless of the variation of the surface charge, indicating that transcription was enhanced due to the stabilization of RNA structure by its hydrophobic interaction with liposome. Translation was inhibited by cationic liposome although it was enhanced by anionic liposome and neutral liposome. On the other hand, the folding was not inhibited in the presence of neutral liposome, whereas anionic liposome and cationic liposome inhibited the folding in proportion to the their surface charges, suggesting that the total GFP expression was controlled by a charged liposome in the translation step and folding step.

The effective production and secretion of chitosanase from S. griseus cells, in the presence of hydrogen peroxide, were studied by the treatment of the cells with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) liposomes under heat condition. The variation of the conformation and activity of the chitosanase caused by the interaction of liposomes with target chitosanase under stress condition was systematically investigated by using circular dichroism (CD) spectra and dielectric dispersion analysis (DDA). The effect of the oxidative stress (hydrogen peroxide) on the lipid and protein peroxide of cell membrane of S. griseus pretreated with and without liposomes under heat stress at 41 degrees C was further carried out. The possible utilization of membrane-membrane interaction between liposomes and cell membrane induced by the heat treatment was further investigated to enhance the production of chitosanase from S. griseus under oxidative stress condition.

A direct interaction of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) liposomes with membrane of Streptomyces griseus cell under the heat stress at 41 degrees C increased the chitosanase production and release to 2.2 times higher than that at 37 degrees C without the POPC liposomes. Amount of chitosanase released across the lipid mimicking cell membrane (LMCM) liposome under a heat at 41 degrees C in the presence of POPC liposomes was 17% of initially-entrapped chitosanase while it was only 1% in the absence of POPC liposomes, even under a heat stress at 41 degrees C, clearly showing the importance of the direct interaction between membrane and membrane.