The Autolytic Enzyme System of Streptococcus faecalis. II. Partial Characterization of the Autolysis and Its Substrate^*

Abstract

A soluble autolysin has been isolated from cell walls of exponential (log) phase cultures of Streptococcus faecalis ATCC 9790 by means of gel filtration of trypsin-activated wall lysates. Trypsin and other proteolytic enzymes speed wall autolysis apparently by "activating" the autolysin. The autolysin seems to be closely associated with the wall as virtually complete wall dissolution is a prerequisite for obtaining the enzyme in solution. While the soluble autolysin can act on walls of S. faecalis and Micrococcus lysodeikticus, it is virtually inactive on walls from several other bacterial species, Borohydride reduction indicates P revious studies (Shockman, 1963b(Shockman, , 1965Shockman et al., 1958 Shockman et al., , 1961Toennies and Shockman, 1958;Conover et al., 1966) have demonstrated that cells from exponential phase (log) cultures of Streptococcus faecalis 9790 will autolyze rapidly when placed under environmental conditions which prevent the continued synthesis of cell wall peptidoglycan (mucopeptide, glycopeptide, or murein). Inhibition of peptidoglycan synthesis (resulting in autolysis) can be caused either by the addition of a specific inhibitor, such as penicillin or cycloserine, or by deprivation of a nutritionally essential precursor of wall peptidoglycan, such as L-lysine, D-alanine, aspartic and glutamic acids, or glucose.The potential for cell autolysis reached a maximum toward the end of the exponential growth phase and thereafter the cells became resistant to autolysis (Shockman, 1965). Stationary-phase, valine-deprived (Val) or threonine-deprived (Thr) cultures resist autolysis (Shockman, 1965 ; Shockman et al., 1961).Two observations implicated an enzymatic attack on the rigid and protective cell wall as the initial step in cell autolysis. First, when an osmotically protective agent, such as 0.5 M sucrose, was provided, wallfree spherical, osmotically fragile protoplasts could be obtained from log cells, but not from stationaryphase Thr cells in the absence of an exogenous lytic ~~~

Abnormal Autolytic Enzyme in a Pneumococcus with Altered Teichoic Acid Composition

“…Thus, sensitivity to streptolysins was correlated with the presence of alanine-containing teichoic acids in streptococci (7). The specific autolytic activity of a staphylococcal mutant that is defective in teichoic acid was much lower than that of the wild type (8); sensitivity of Streptococcus faecalis cell walls to the homologous autolytic muramidase was somewhat decreased after the removal of teichoic acid (9). Pneumococcal cell walls "stripped" of their teichoic acid component lose sensitivity to homologous autolysin; cell walls in which the choline component of the teichoic acid was biosynthetically replaced by ethanolamine also become resistant to autolysin (2).…”

Lysis of Streptococci by an Extracellular Lysin Produced by Competent Group H Streptococcus Strain CHALLIS

“…Recent assays of sterile competence factor-containing solutions prepared in complex media, as well as overnight culture fluids from CHALLIS organisms that lacked competence factor activity, revealed that these contained lytic activity against non-competent WICKY organisms. Since lysis of streptococcal organisms has always been a topic of interest to us and a number of other investigators (Barkulis, Smith, Boltralik & Heymann, 1964;Shockman, Pooley & Thompson, 1967, Coleman, van de Rijn & Bleiweis, 1970, and, since an extracellular lysin derived from group H organisms has never been before described, we undertook the survey to see whether the lysin was group or genus specific.…”

Autolysis ofBacillus colistinus

“…Shockman et al 3 ) reported that trypsin activated latent autolysin in Streptococcus jaecalis. The effects of trypsin on the autolysis of B. colisitnus have not been investigated yet, and the present paper deals with this problem.…”

“…3) reported that trypsin and other proteolytic enzymes accelerated wallautolysis, apparently by activating the latent autolysin. Trypsin-pretreatment of B. colistinus cells grown in glucose-bouillon medium enhanced the rate of autolysis and converted them into lysozyme-sensitive cells.…”