Existence of two phenylalanyl-sRNA synthetases in Neurospora crassa.

Abstract

An unusual cross reaction between Escherichia coli sRNA and Neurospora crassa phenylalanyl-sRNA synthetase discovered by Barnett and Jacobson (1964) was caused by 2 different enzymes, El and E2. El changes phenylalanine to normal E. coli phenylalanine acceptor RNA and does not change Neurospora sRNA. E2 changes phenylalanine to other sRNA''s of E. coli than normal phenylalanine acceptor RNA, but does change phenylalanine to Neurospora sRNA. The difference between the 2 enzymes can be shown directly by DEAE cellulose fractionation and also by polyvinyl sulfate or bentonite inhibition of E2 enzyme activity. No sRNA corresponding to El in various stages of the life cycle of Neurospora was detected. The pattern of cross reactions by these 2 enzymes with sRNA''s from various organisms indicates that El enzyme is similar to bacterial phenylalanyl -sRNA and E2 to higher organisms.