Abstract
Abstract Stringent cells of Escherichia coli (rel+) cease growth and protein, RNA, and lipid synthesis when deprived of a required amino acid; relaxed cells (rel-) cease growth and protein synthesis but continue lipid synthesis when deprived of a required amino acid, as assayed by [14C]acetate incorporation. When phospholipid synthesis was assayed by using 32Pi, some net synthesis does occur, but the majority of the incorporation is a consequence of rapid breakdown and resynthesis (turnover) of phosphatidylethanolamine, normally a stable component of the cell envelope.
Highlights
When phospholipid synthesis was assayed by using s2Pi, some net synthesis does occur, but the majority of the incorporation is a consequence of rapid breakdown and resynthesis of phosphatidylethanolamine, normally a stable component of the cell envelope
A great deal of attention has centered on the effects of stringent and relaxed control of RNA synthesis (3, 4; see general reviews, 5, 6), a variety of other processes are apparently affected, including translation of RNA into protein (7), phage
Lipid biosynthesis was followed by cletermiiiiug the amount of [‘%‘Iacsetate incorporated into lipid
Summary
Stringent cells of Escherichia co2i (reZ+) cease growth and protein, RNA, and lipid synthesis when deprived of a required amino acid; relaxed cells (re2-) cease growth and protein synthesis but continue lipid synthesis when deprived of a required amino acid, as assayed by [14C]acetate incorporation. When phospholipid synthesis was assayed by using s2Pi, some net synthesis does occur, but the majority of the incorporation is a consequence of rapid breakdown and resynthesis (turnover) of phosphatidylethanolamine, normally a stable component of the cell envelope. When growing bacteria are deprived of a required amino acid they stop growing and quit making protein and stable RNA. The requirement for adequate supplies of amino acids for protein synthesis is apparent; the biochemical basis of the relationship between amino acid starvation and stable RNA synthesis is not understood (I). Gene) in contrast to wild type or stringent (Tel+) organisms synthesize ribosomal and transfer RNA at nearly the normal rate (2) growth and protein synthesis have essentially stopped. A primary difference in phospholipid metabolism between stringent and relaxed organisms seems to be a marked turnover of phosphatidylethanolamine, the major, normally stable phospholipid in these organisms, in amino acid-starved, relaxed cells
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