Effects of Polynucleotides on Production and Activity of Streptolysin S

Activity of various natural and synthetic polynucleotides as a carrier for streptolysin S was tested in a resting cell system. As the carrier, intact molecules of MS2 RNA, E. coli tRNA or rat liver RNA were almost inactive, whereas RNase I core of these RNAs, especially the core-frac­tions eluted from DEAE-cellulose column at higher NaCl concentrations, effectively induced pro­duction of the extracellular hemolysin. The carrier activity of yeast RNA was significantly en­hanced by simultaneous addition of RNase I, to the streptococcal suspension. Preincubation of yeast RNA with growing streptococci or a protein fraction from the bacterial culture supernatant increased its carrier activity. Evidences were obtained suggesting involvement of streptococcal nuclease in the enhancement of the carrier effect. Production of the streptococcal hemolysin was markedly promoted by polyguanylic acid but neither by polyadenylic acid, polycytidylic acid nor by polyuridylic acid. Like trypan blue, polyguanylic acid exerted potent inhibitory effect on hemolytic activity of streptolysin S complex. Similar but less marked effect was observed with certain RNase I core fractions of rat liver RNA. Some data concerning effect of polynucleotides on stability of the hemolysin were also presented.