Overexpression of Escherichia coli single stranded DNA binding protein under bacteriophage T 7 promoter

A recombinant vector for overproduction of the E. coli single stranded DNA binding protein (E. coli SSBP) has been constructed. An E. coli strain carrying this plasmid produces up to 150 mg pure SSBP per litre of bacterial culture in a laboratory shake flask. Electron microscopy of the single stranded DNA complexed with SSBP shows characteristic "beaded string"-like appearance. Strong clustering of protein molecules on ssDNA is indicative of a highly cooperative binding.