A large operon-type structure has been located between the gltA and citB loci on the Bacillus subtilis chromosome. On the basis of the analysis of the 25 kb sequenced so far, it potentially encodes at least three large proteins which contain structural motifs associated with the subunits of all characterized peptide synthases. The amino acid recognition specificity of this new peptide synthase is discussed in the light of sequence homology with other synthases.