Biosynthesis of arginine in L cells infected with chlamydiae.

Three members of the genus Chlamydia were examined for their ability to synthesize arginine, an ability their L cell (mouse fibroblasts) hosts lacked. C. psittaci (strain 6BC) multiplied in arginine-free medium 199 without significant decrease in titer and incroporated (14)C-glutamate and (14)C-ornithine into the arginine fraction of its protein. In arginine-free media, C. trachomatis (strain mouse pneumonitis) and C. psittaci (strain meningopneumonitis) grew to only 1 to 10% of the titer obtained in arginine-containing media. The decreased ability of these two strains to multiply in arginine-free media was paralleled by a decreased ability of infected host cells to incorporate (14)C-glutamate into protein arginine. These results suggest that chlamydiae either synthesize arginine themselves, or, in some unknown manner, cause their host cells to do so.