HIGH-LEVEL EXPRESSION OF HUMAN SUPEROXIDE-DISMUTASE IN THE CYANOBACTERIUM ANACYSTIS-NIDULANS-6301

A chemically synthesized gene encoding human CuZn superoxide dismutase (hSOD) was cloned into the shuttle vector pBAX18R and expressed in An acystis nidulans 6301 (Synechococcus sp. strain PCC 6301) under the co ntrol of a ribulose-1,5-bisphosphate carboxylase/oxygenase gene (rbc) promoter derived from A. nidulans 6301. The sequences immediately upst ream from the hSOD coding region and the distances between the ribosom al binding site and ATG initiation codon strongly affected the express ion of the hSOD gene in A. nidulans cells. Optimal expression of hSOD was obtained with the expression vector pBAXSOD8-I, which contained a GGAGAG sequence. In defined conditions, irradiation with light increas ed hSOD enzyme activity in the transformants > 18-fold and the level o f the hSOD protein reached a value of about 3% of the total soluble pr otein. The transformants that expressed hSOD acquired the ability to e xtenuate photooxidative damage induced by methyl viologen.