Transduction of Cu,Zn-superoxide dismutase mediated by an HIV-1 Tat protein basic domain into mammalian cells

A human Cu,Zn-superoxide dismutase (Cu,Zn-SOD) gene was fused with a gene f ragment encoding the nine amino acid transactivator of transcription (Tat) protein transduction domain (RKKRRQRRR) of HIV-1 in a bacterial expression vector to produce a genetic in-frame Tat-SOD fusion protein. The expressed and purified Tat-SOD fusion protein in Escherichia coli can enter HeLa cell s in a time- and dose-dependent manner when added exogenously in a culture media. Denatured Tat-SOD protein was transduced much more efficiently into cells than were native proteins. Once inside the cells, transduced Tat-SOD protein was enzymatically active and stable for 24 h, The cell viability of HeLa cells treated with paraquat, an intracellular superoxide anion genera tor, was increased by transduced Tat-SOD, These lines of results suggest th at the transduction of Tat-SOD fusion protein may be one of the ways to rep lenish the Cu,Zn-SOD in the various disorders related to this antioxidant e nzyme. (C) 2000 Federation of European Biochemical Societies, Published by Elsevier Science B.V. All rights reserved.