Abstract |
Bacillus stearothermophilus reacted to pseudomonic acid-induced inhibition of isoleucine-transfer ribonucleic acid ( RNA) acylation and to energy downshift caused by alpha-methylglucoside addition with accumulation of guanosine 3',5'-polyphosphates [( p)ppGpp] and restriction of RNA synthesis. In vitro studies indicated that ( p)ppGpp was synthesized by two different enzymes. One enzyme, ( p)ppGpp synthetase I, was present in the ribosomal fraction, required the addition of a ribosome- messenger RNA- transfer RNA complex for activation, and was inhibited by tetracycline and thiostrepton. It is suggested that ( p)ppGpp synthetase I is comparable to the relA gene product from Escherichia coli and is responsible for ( p)ppGpp accumulation during amino acid starvation. The other enzyme, ( p)ppGpp synthetase II, was found in the high-speed supernatant fraction (S100). It functioned independently of ribosomes, transfer RNA, and messenger RNA and was not inhibited by the above-mentioned antibiotics. ( p)ppGpp synthetase II is thought to be responsible for ( p)ppGpp accumulation during carbon source downshift. The two enzymes differ in their Km values for adenosine triphosphate ( ATP):2mM ATP for synthetase I and 0.05 mM ATP for synthetase II. They also have different molecular weights: apparent Mr of 86,000 (+/- 5,000) for synthetase I and 74,000 (+/- 5,000) for synthetase II.
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Authors | S Fehr, D Richter |
Journal | Journal of bacteriology
(J Bacteriol)
Vol. 145
Issue 1
Pg. 68-73
(Jan 1981)
ISSN: 0021-9193 [Print] United States |
PMID | 6161916
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
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Chemical References |
- Guanine Nucleotides
- RNA, Bacterial
- RNA, Messenger
- Guanosine Tetraphosphate
- Guanosine Pentaphosphate
- RNA, Transfer
- Ligases
- guanosine 3',5'-polyphosphate synthetases
- Glucose
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Topics |
- Geobacillus stearothermophilus
(enzymology)
- Glucose
(metabolism)
- Guanine Nucleotides
(biosynthesis)
- Guanosine Pentaphosphate
(biosynthesis)
- Guanosine Tetraphosphate
(biosynthesis)
- Ligases
(metabolism)
- RNA, Bacterial
(metabolism)
- RNA, Messenger
(metabolism)
- RNA, Transfer
(metabolism)
- Ribosomes
(enzymology)
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