RNA-synthesizing enzymes in healthy and TMV-infected tobacco leaves. Separation and properties of enzymes catalyzing nucleotide polymerization

A separation procedure, preparation of the extract and a gel filtration on 8% agarose, has been developed for the separation of enzymes catalyzing nucleotide polymerization in healthy and TMV-infected tobacco leaves. The profiles of the gel filtrations were almost the same from infected and uninfected materials. A number of nucleotide polymerizing and nucleolytic activities were revealed. A DNA-directed RNA polymerase was demonstrated as well as three homopolymerase activities. Incorporations of ATP and CTP, requiring a primer (preferentially tRNA), were found in the same fractions and were probably caused by the same enzyme. An incorporation of GTP using poly(G) as primer likewise was detected. These polymerizations were inhibited in the presence of 10 mm pyrophosphate while 100 mm orthophosphate was not inhibitory. Furthermore, two peaks of nuclease activities have been found. The slow-eluting peak indicates an enzyme (enzymes) of approximately the same size as pancreatic ribonuclease (M_r = 13,680). The fast-eluting peak corresponds to molecular weights of the order of 150,000.