Identification and gene structure of an azurin-like protein with a lipoprotein signal peptide in Neisseria gonorrhoeae

We have determined the DNA sequence of a cloned gonococcal gene and found that the predicted protein sequence is highly homologous to the class of blue copper-containing proteins known as azurins. However, the 127 amino acid sequence homologous to azurin is preceded by two unusual structural features. The gene possesses a typical 17 residue lipoprotein signal peptide and the N-terminal 39 amino acids are very rich in proline and alanine. The azurin gene of Pseudomonas aeruginosa has recently been characterized and possesses an ordinary signal peptide susceptible to signal peptidase I, causing export of a soluble protein to the periplasm. In gonococcus it would appear that the homologous product becomes an outer membrane protein.