Expression and secretion of human atrial natriuretic α-factor in Bacillus subtilis using the subtilisin signal peptide

Abstract Using the signal peptide of the Bacillus subtilis subtilisin gene ( aprE ) and a synthetic cDNA corresponding to the mature region of the human atrial natriuretic α-factor (hANF), we have constructed a secretion vector. B. subtilis cells, when transformed with this vector, secrete immunoreactive hANF peptides into the medium at about 500 μg/liter. The hANF is the first human gene product to be secreted from B. subtilis using this signal peptide. We have used promoters active during vegetative growth or sporulation and hosts deficient in several extracellular proteases but some proteolysis of the secretion products still occurs. In addition, both cell growth and sporulation are adversely affected by hANF production. Possible explanations for this observation are inefficient secretion of the atrial hormone or toxicity of the precursor or mature peptide.