OCCURRENCE OF ENZYMES OF ARGININE DIHYDROLASE PATHWAY IN SPIROPLASMA CITRI

Abstract

Cell-free extract of California strain of Spiroplasma cirri contained activities of arginine deiminase, ornithine transcarbamylase, and carbamyl phosphokinase but not those of argininosuccinic acid sythetase, argininosuccinase, and arginase. When washed cells suspended in buffer were supplied with arginine, the disappearance of arginine was accompanied by appearance of citrulline, ornithine, and ammonia. Addition of rifampicin or cycloheximide to culture medium at the time of inoculation prevented the appearance of activity of arginine deiminase, the first enzyme of arginine dihydrolase pathway. These results show that arginine degradation in S. citri is via arginine dihydrolase pathway and that arginine deiminase, and possibly the other two enzymes of this pathway, are inducible.