Effect of cerulenin on cellular autolytic activity and lipid metabolism during inhibition of protein synthesis in Streptococcus faecalis.

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RESUMO

Cellular autolytic activity as well as lipid and lipoteichoic acid metabolism have been studied in cultures of Streptococcus faecalis receiving various combinations of the following treatments: chloramphenicol addition, starvation for an essential amino acid (valine), and cerulenin treatment. Lipoteichoic acid initially accumulated in chloramphenicol-treated and amino acid-starved cells and decreased relative to the cellular mass in cerulenin-treated cells. The relative phosphatidylglycerol content of amino acid-starved cultures or of cultures treated with either antibiotic rapidly decreased upon initiation of each treatment. In all cases, cerulenin initially stimulated diphosphatidylglycerol synthesis. Pretreatment of cultures with cerulenin prevented the inhibition of cellular synthesis autolysis normally observed during chloramphenicol treatment, but did not affect amino acid starvation-induced inhibition of autolytic activity. Variations in the levels of the nonionic lipid fraction, predominantly diglycerides, correlated best with the patterns of autolytic activity observed during chloramphenicol treatment, whereas variations in the levels of diphosphatidylglycerol and lipoteichoic acid correlated best with the patterns of autolytic activity observed during amino acid starvation. Components of the nonionic lipid fraction were demonstrated to inhibit autolytic activity 50% in whole cell and in cell wall assays at 60 and 120 nmol/mg (dry weight), respectively.

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