Dependence of Protease Secretion by Streptococcus faecalis var. liquefaciens on Arginine and Its Possible Relation to Site of Synthesis

Abstract

Washed cells of Streptococcus faecalis var. liquefaciens , when harvested from media that supported protease biosynthesis, continued to release this extracellular enzyme in phosphate buffer. The addition of ethylenediaminetetraacetic acid (EDTA) halted the secretion. If zinc ions were added to the EDTA-treated cells before 45 to 60 min had elapsed, a fraction of the anticipated enzyme activity was observed. After 60 min, arginine and phosphate, in addition to zinc, were necessary for the demonstration of proteolytic activity. The enzyme that was released was newly formed, because chloramphenicol, puromycin, or actinomycin D prevented its appearance. Energy for this synthetic reaction was obtained, apparently, from arginine; lactose could not be substituted for arginine. This last point is interpreted to mean that extracellular protease biosynthesis occurs in a localized area or cellular compartment into which the adenosine triphosphate derived from the fermentation of lactose cannot diffuse. No evidence was found for a protease zymogen, although this possibility is not completely precluded.