Enhanced production of pL-controlled recombinant proteins and plasmid stability in Escherichia coli RecA+ strains.

Overexpression of pL-controlled foot-and-mouth disease virus recombinant proteins was studied in Escherichia coli RecA+ strains and in a recA mutant. Higher protein yield and extractable plasmid DNA amounts were found in wild type cells, in absence of detectable RecA proteolytic activity. Minor but still significant differences in pBR322 DNA amounts were also detected between RecA+ and its recA13 and lexA1 derivatives. These data should be seriously considered to select expression systems and to design production processes for recombinant proteins, specially if they are expected to be toxic for Escherichia coli cells.