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Understanding (p)ppGpp-mediated Mechanisms of Persistence and Stress Survival in Bacillus subtilis
Başlık:
Understanding (p)ppGpp-mediated Mechanisms of Persistence and Stress Survival in Bacillus subtilis
Yazar:
Barra, Jessica Tse, author.
ISBN:
9780438159679
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (261 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-11(E), Section: B.
Advisors: Jue D. Wang Committee members: Richard Gourse; Patricia Kiley; Michael Thomas; Kalin Vetsigian.
Özet:
During amino acid starvation, the Gram-positive bacterium Bacillus subtilis, produces a molecule called (p)ppGpp, a nucleotide derived from GTP or GDP and ATP. This molecule is produced by almost all bacteria but its effects are best characterized in E. coli and B. subtilis. In E. coli and B. subtilis , (p)ppGpp shuts down cellular processes such as ribosomal RNA transcription, translation, and DNA replication. Cells without (p)ppGpp, called (p)ppGpp 0, cannot grow on minimal media and are auxotrophic for several amino acids. In this work, we showed that B. subtilis (p)ppGpp 0 cells were auxotrophic for valine, leucine, isoleucine (branched chain amino acids), methionine, threonine, and mildly for histidine, arginine, and tryptophan. The auxotrophy is due to hyperrepression of CodY and GTP-dependent processes. We also reveal a new role for (p)ppGpp: protection from and adaptation to amino acid downshift.
We examined the role of (p)ppGpp in mediating persistence, the ability of a subpopulation of bacteria to survive antibiotics for a prolonged period of time. We demonstrate that (p)ppGpp is one mechanism of persister formation and is necessary and sufficient to promote persistence. The most striking discovery is that (p)ppGpp antagonism of GTP is essential for persistence. We also show that there are diversified roles for the (p)ppGpp synthetases, allowing for production of varying levels of (p)ppGpp in individual cells as a bet-hedging strategy and through responsive mechanisms, all to ensure stress survival.
(p)ppGpp and GTP-dependent mechanisms protect cells against bacteriostatic antibiotics. We treated wild type and (p)ppGpp0 cells with chloramphenicol and saw that (p)ppGpp0 cells lose viability. Interestingly, RelA was the primary (p)ppGpp synthetase that produced (p)ppGpp to protect cells against chloramphenicol. (p)ppGpp antagonism of GTP levels also correlates with chloramphenicol survival. Thus, (p)ppGpp inhibition of GTP is also critical for protection against bacteriostatic antibiotics. This response appears to only occur in the soil-dwelling B. subtilis, since the intestine-inhabiting E. coli does not produce (p)ppGpp in response to chloramphenicol, indicating that (p)ppGpp induction by bacteriostatic antibiotics may be niche-dependent.
In this work, we comprehensively examined the role of (p)ppGpp in mediating stress survival in persistence.
Notlar:
School code: 0262
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(688289.1) | 688289-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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