THE CLONING AND CHARACTERIZATION OF THE AROM GENE OF PNEUMOCYSTIS-CARINII

The arom gene, encoding a single polypeptide that catalyses five conse cutive steps of the pre-chorismate aromatic amino acid biosynthetic pa thway, has been cloned from the opportunistic pathogen Pneumocystis ca rinii. There is a single open reading frame of 4788 bp which includes an intron of 45 bp that does not introduce a stop codon into the seque nce. Thus, the derived amino acid sequence consists of 1581 residues, which is highly homologous to all fungal AROM proteins studied to date . These data support the view that P. carinii is a fungus and imply th at its aromatic amino acid biosynthesis is conventionally organized.