Arginine Synthesis in Proteus mirabilis

SUMMARY Twenty-nine arginine auxotrophs of Proteus mirabilis strain 13 have been divided into eight groups which represent different biochemical blocks in the arginine biosynthetic pathway. The mutants were classified according to their growth requirements, syntrophism, accumulation of intermediates and enzyme deficiencies. The steps in the pathway are the same as those of Escherichia coli although mutants will not utilize N-α-acetyl-l-ornithine or N-acetyl-l-glutamate. However, these two substances were shown to be intermediates. Ornithine is synthesized via the linear route common to entero-bacteria and not by transacetylation between N-α-acetyl-l-ornithine and l-glutamate as in some other bacteria and yeasts.