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S Waks

Publications and source records attributed to S Waks.

4 recordsLinked to original sources
PubMed1978

Secretion of cell wall polymers into the growth medium of lysis-defective pneumococci during treatment with penicillin and other inhibitors of cell wall synthesis.

Autolysin-defective pneumococci secrete into the growth medium choline-containing macromolecules during treatment with any one of a large number of inhibitors of cell wall biosynthesis, including beta-lactams, beta-halogeno-d-alanines, cephalosporins, and d-cycloserine. Secretion is closely related to the dose response of the bacteria to the various drugs: (i) secretion can already be detected at the minimum inhibitory concentration; (ii) the rate and extent of secretion is dependent upon the drug concentration; and (iii) secretion commences within minutes after the addition of the antibiotics to the cultures. Reversal of the growth-inhibitory effect of benzylpenicillin (by penicillinase addition) is accompanied by a halt in secretion just at the time when the bacteria resume normal growth. Secretion of the choline-containing macromolecules seems to be a specific consequence of the inhibition of peptidoglycan biosynthesis, since inhibition of growth by drugs affecting protein, ribonucleic acid, or deoxyribonucleic acid synthesis does not cause secretion. The choline-containing macromolecules include both the pneumococcal lipid-containing teichoic acid (Forssman antigen) and wall teichoic acids made after the addition of antibiotics. The appearance of these macromolecules in the growth medium is not due to the hydrolytic activity of an autolysin, since penicillin-induced secretion could be demonstrated in autolysin-defective mutants, in pneumococci grown on ethanolamine-containing medium (such cells are known to have defective autolytic systems), and in wildtype pneumococci grown under conditions nonpermissive for lysis.

Antimetabolites↗
PubMed1978

Characterization of cell wall polymers secreted into the growth medium of lysis-defective pneumococci during treatment with penicillin and other inhibitors of cell wall synthesis.

Autolysin-defective pneumococci secrete large quantities of choline-containing cell wall polymers into the growth medium during treatment with inhibitors of peptidoglycan synthesis. The secreted polymers were separated into three fractions by a combination of gel filtration on agarose and sodium dodecyl sulfate-gel electrophoresis. Fraction I had a high apparent molecular size and contained the Forssman antigen in complex with material exhibiting properties of cell wall teichoic acid. Choline-containing polymers of as yet uncharacterized structure were present in both fractions IIA and IIB, and fraction IIA also contained peptidoglycan components.

Antibodies, Bacterial↗
PubMed1975

Mechanism of action of penicillin: triggering of the pneumococcal autolytic enzyme by inhibitors of cell wall synthesis.

During penicillin treatment of an autolysin defective mutant pneumococcus we have observed three novel phenomena: (i) Growth of the mutant cultures is inhibited by the same concentrations of penicillin that induce lysis in the wild type. (ii) Mutant bacteria treated with the minimum growth inhibitory concentration of penicillin will lyse upon the addition of wild-type autolysin to the growth medium. Chloramphenicol and other inhibitors of protein synthesis protect the cells against lysis by exogenous enzyme. Sensitivity of the cells to exogenous autolysin requires treatment with penicillin or other inhibitors of cell wall synthesis (e.g., D-cycloserine or fosfonomycin) since exogenous autolysin alone has no effect on bacterial growth. (iii) Treatment with penicillin (or other inhibitors of cell wall synthesis) causes the escape into the medium of a choline-containing macromolecule that has properties suggesting that it contains pneumococcal lipoteichoic acid (Forssman antigen). Each one of these three phenomena (growth inhibition, sensitization to exogenous autolysin, and leakage of lipoteichoic acid) shows the same dose response as that of the penicillin-induced lysis of wild-type pneumococci. On the basis of these findings we propose a new hypothesis for the mechanism of penicillin-induced lysis of bacteria. It is suggested that inhibition of cell wall synthesis by any means triggers bacterial autolytic enzymes by destabilizing the endogenous complex of an autolysin inhibitor (lipoteichoic acid) and autolytic enzyme. Escape of lipoteichoic acid-like material to the growth medium is a consequence of this labilization. Chloramphenicol protects bacteria against penicillin-induced lysis by interfering with the activity of the autolytic enzyme, rather than by depleting the concentration of the enzyme at the cell surface.

Autolysis↗