THE INCORPORATION OF GLYCEROL AND LYSINE INTO THE LIPID FRACTION OF STAPHYLOCOCCUS AUREUS

Abstract

Incubation of washed cells of S. aureus with [l-14c]glycerol results in the incorporation of glycerol into the lipid fraction of the cells. The rate of incorporation is increased by the presence of glucose and amino-acids. The presence of amino-acids increases incorporation into the fraction containing O-amino-acid esters of phosphatidylglycerol. Glycerol, incorporated into washed cells by incubation with glycerol, glucose and amino-acids, is rapidly released from the lipid fraction when cells are incubated at low suspension densities in buffer. Of nine amino-acids tested, only lysine is significantly incorporated into the lipid fraction. The incorporation is increased by the presence of glycerol, glucose and other amino-acids, especially aspartate and glutamate. The incorporation of lysine is increased by the addition of puromycin at concentrations that inhibit protein synthesis. Chloramphenicol does not increase the incorporation of lysine but abolishes the enhancing effect of puromycin. The enhancing effect of puromycin is accompanied by a similar increase in the incorporation of lysine into the fraction soluble in hot trichloroacetic acid. Lysine is incorporated into the lipid fraction that contains O-amino acid esters of phosphatidylglycerol and corresponds in properties to phosphatidylglyceryl-lysine. Lysine is rapidly released from the lipid of cells incubated in buffer only at low suspension densities. Incubation of cells with the phosphatidylglyceryl-lysine fraction does not lead to the appearance of free lysine or to incorporation into the fraction insoluble in hot trichloroacetic acid.