Expression in Escherichia coli of a synthetic gene coding for horse heart myoglobin

A gene for expression of horse heart myoglobin in Escherichia coli has been constructed in one step from long synthetic oligonucleotides. The synthetic gene contains an efficient translation initiation signal and used codons that are commonly found in E. coli. Unique restriction sites are placed throughout the gene. It has been inserted in a phagemid vector and is expressed from the lac promoter in E. coli at high efficiency, the soluble heme protein representing approximately 10% of soluble protein. Two versions of horse heart myoglobin were produced with aspartic acid or asparagine at residue 122. Comparison of chromatographic mobilities of these two proteins with authentic horse heart myoglobin identified aspartic acid as the correct residue 122. The availability of this gene, which is designed to facilitate oligonucleotide mutagenesis or cassette mutagenesis, will allow systematic structure-function analysis of horse heart myoglobin.