A 24-amino-acid polypeptide is essential for the biosynthesis of the coenzyme pyrrolo-quinoline-quinone

At least four genes are required for the biosynthesis of the coenzyme pyrrolo-quinoline-quinone (PQQ) in Acinetobacter calcoaceticus. The DNA region where one of these genes was mapped codes for a polypeptide of only 24 amino acids. Here we show that indeed this small peptide is essential for PQQ synthesis. Site-directed mutagenesis shows that at least one glutamate and one tyrosine residue of the polypeptide are essential for its function.