Studies on the cellular functions of lipid-modified proteins

点击翻译按钮获取中文摘要

Many cellular proteins are modified with lipids such as acyl(palmitoyl or myristoly)and/or prenly(farnesly or geranylgeranyl)residues. In this researach project, the biochemical functions of lipid-modified proteins were studied and searaach for microbial inhibitors of their formation wes carried out as a new approach for anticancer or antiviral agents.HIV Gag protein is myrisstoylataed at the N-terminal glycine residue, which plays an important role in virus particlebdding. The myristoylation levels were controlled to investigate the effect on the particle budding by using the specifiv acyl-CoA synthetase inhibitor triacsin previousy discovered by our group. We showed that the inhibition of Gag myristoylation by triacsin follows dose-dependent kinetics but that the particle budding exhibits sudden shutoff kinetics, suggesting that only a relatively small proportion of total Gag molecules need to be myristoylated for efficient budding and indicating that total inhibition of myristoylation will be required for effective anti-HIV therapy.Oncogene product Ras proteins are posttranslationally farnesylated at the cysteine residue near the C-terminus, in which protein farnesyltransferase(PFTase)is involved. PFTase is expected as a novel target of inhibition since the inhibition causes altering membrane localization and blocking activation of Ras proteins. An efficient screening system was conducted by utilizing Saccharomyces cerevisiae, resulting in discovery of two series of new PTFase inhibitors, andrastins produced by Penicillium sp.FO-3929 and kurasoins by Paecilomyces sp.FO-3684. The structure elucidation including stereochemistries, biosynthesis of andrastin and total sylnthesis of kurasoin were studied. Their inhibitory activity against PFTase (IC_<50>) was 10-60muM.It still remains to be investigated whether or not these compounds inhibit PFTase in cells and show in fvivo anticancer activity.