Stable Ribonucleic Acid Synthesis in Stringent (rel+) and Relaxed (rel−) Polyamine Auxotrophs of Escherichia coli K-12
AUTOR(ES)
Srinivasan, P. R.
RESUMO
The relationship of polyamines to stable ribonucleic acid (RNA) synthesis under conditions of amino acid withdrawal or chloramphenicol treatment was examined with the use of a closely related rel+, rel− pair conditionally incapable of synthesizing putrescine. Under conditions of polyamine starvation, the cellular sperimidine level fell to one-third to one-half of the value observed in putrescine-supplemented cultures and putrescine became undetectable; cadaverine was synthesized by both strains, but the relaxed strain, MA 252, accumulated less cadaverine per cell than its stringent twin, MA 254. Upon amino acid withdrawal, the stringent strain remained stringent whether starved of or supplemented with polyamines. Similarly, the relaxed strain was capable of making RNA either with or without polyamine starvation. On the addition of chloramphenicol or upon amino acid withdrawal in the relaxed strain, supplementation with spermidine had no effect on the initial rate of RNA synthesis, although RNA accumulation was greater in the presence of added spermidine. Spermidine added at the conclusion of RNA synthesis prompted additional synthesis, although preincubation with spermidine again had no effect on the initial rate. All forms of stable RNA species were made with polyamine supplementation. The present data appear to rule out the possibility that polyamines are primary causative agents in stimulating RNA synthesis, but rather suggest an indirect or secondary role for spermidine in which the polyamines “stimulate” stable RNA synthesis probably by relieving RNA product inhibition of RNA synthesis.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=285429Documentos Relacionados
- Synthesis of Ribonucleic Acid and Protein in Plasmid-Containing Minicells of Escherichia coli K-12
- Messenger Ribonucleic Acid Stability in Relaxed and Stringent Escherichia coli Starved for Methionine
- Deoxyribonucleic Acid-Directed In Vitro Synthesis of ilv-Specific Messenger Ribonucleic Acid by Extracts of Escherichia coli K-12
- Regulation of polyamine and streptomycin transport during stringent and relaxed control in Escherichia coli.
- Transient growth inhibition of Escherichia coli K-12 by ion chelators: "in vivo" inhibition of ribonucleic acid synthesis.