Arginine biosynthesis in Legionella pneumophila: absence of N-acetylglutamate synthetase

Legionella pneumophila was unable to grow in a chemically defined medium without arginine because it could not carry out the first step in the biosynthetic pathway, the conversion of glutamate to N-acetylglutamate. All strains examined could grow when N-acetylglutamate (or other later arginine precursors) were substituted for arginine. No activity corresponding to N-acetylglutamate synthetase could be detected in cell extracts of L. pneumophila.