Complete nucleotide sequence of the penicillin acylase gene from Kluyvera citrophila

The penicillin acylase (PAC) from Kluyvera citrophila ATCC21285 has been purified to homogeneity and found to be composed of two non-identical subunits of 23 and 62 kDa, in contrast with the previous findings [Shimizu et al., Agr. Biol. Chem. 39 (1975) 1655-1661]. The nucleotide (nt) sequence of the K. citrophila pac gene contained in the 3-kb PvuI-HindIII fragment of pKAP1 [García and Buesa, J. Biotechnol. 3 (1986) 187-195] has been determined, showing that it encodes a protein of 844 amino acid (aa) residues. The aa analysis of the N-terminal and C-terminal sequences of the purified subunits showed that they were derived from a common precursor protein of 93.5 kDa, from which a signal peptide of 26 aa, responsible for the periplasmic translocation of the protein, and an internal connecting polypeptide of 54 aa, have been removed in the maturation of the PAC. The comparison of the nt sequences of the pac genes from K. citrophila and Escherichia coli ATCC11105 [Schumacher et al., Nucl. Acids Res. 14 (1986) 5713-5727] revealed 80% homology, suggesting a common ancestral pac gene origin. The results reported here should allow investigation of the unusual mechanism of maturation of this prokaryotic protein, as well as manipulation, using DNA recombinant techniques, of the catalytic properties of this industrially important enzyme.