Growth and Macromolecular Composition of a Mutant of Escherichia coli During Polyamine Limitation

Abstract

A mutant of Escherichia coli with reduced levels of biosynthetic arginine decarboxylase was isolated which required putrescine or spermidine for optimal growth. The stimulation of growth by putrescine was 1.5to 3-fold depending upon the culture medium. Specificity studies supported the concept that the requirement was for spermidine or closely related polyamines, or for diamines which could be converted enzymatically to these compounds. The behavior of the macromolecular composition of the polyamine-starved cells appeared abnormal. The ribonucleic acid to protein and deoxyribonucleic acid to cell ratios in the starved cells were both higher than expected on the basis of their growth rate. The stable ribonucleic acid in the polyamine-limited cells appeared to be normal as judged from size distribution and degree of methylation. The relationship of these results to mechanisms for regulation of nucleic acid and protein synthesis in E. coli is discussed.Although the polyamines putrescine, spermi-

Isolation, characterization, and mapping of Escherichia coli mutants blocked in the synthesis of ornithine decarboxylase

“…The necessity of putrescine biosynthesis for normally growing E. coli cells was demonstrated by the Tabors (20), who showed that even under severe arginine-ornithine restriction an ornithine auxotroph used 5 to 18% of the supplementary arginine or ornithine for polyamine biosynthesis during growth in a chemostat. Similarly, strains deficient for AUH and arginine decarboxylase activity (6,14) showed distinct retardation of growth when polyamine depletion was accomplished through growth of strains in high concentrations of arginine. The present study demonstrates nonconditional putrescine dependency in E. coli.…”

Polyamines in microorganisms.

“…Mutants lacking biosynthetic arginine decarboxylase. Mutants have been reported that are deficient in the biosynthetic form of arginine decarboxylase (64,105,135,136,203); deletion mutants that completely lack the enzyme have also been obtained (64,208). The gene for biosynthetic arginine decarboxylase (speA) has been located at 62.8 min on the E. coli chromosome and is very close to the gene for agmatine ureohydrolase (speB (24,105).…”

Effect of Norspermidine and Its Related Triamines on the Cell‐Free Polyphenylalanine Synthesizing System from Vibrio parahaemolyticus

“…Such a functional interchangeability with the structurally related triamines has been observed in the E. coli system, where conversely Nspd and AP-Cad are almost as effective as Spd (12,21). Furthermore, in polyaminedeficient mutants of E. coli, Nspd is a substitute for Spd in supporting growth (17). Recently, it has been shown in E. coli that the sites in the translational machinery at which Spc1 is acting are in the specific regions of ribosomal RNAs (11).…”