The stress sigma factor of RNA polymerase RpoS/σS is a solvent-exposed open molecule in solution.
Biochem J
; 475(1): 341-354, 2018 01 15.
Article
em En
| MEDLINE
| ID: mdl-29229758
ABSTRACT
In bacteria, one primary and multiple alternative sigma (σ) factors associate with the RNA polymerase core enzyme (E) to form holoenzymes (Eσ) with different promoter recognition specificities. The alternative σ factor RpoS/σS is produced in stationary phase and under stress conditions and reprograms global gene expression to promote bacterial survival. To date, the three-dimensional structure of a full-length free σ factor remains elusive. The current model suggests that extensive interdomain contacts in a free σ factor result in a compact conformation that masks the DNA-binding determinants of σ, explaining why a free σ factor does not bind double-stranded promoter DNA efficiently. Here, we explored the solution conformation of σS using amide hydrogen/deuterium exchange coupled with mass spectrometry, NMR, analytical ultracentrifugation and molecular dynamics. Our data strongly argue against a compact conformation of free σS Instead, we show that σS adopts an open conformation in solution in which the folded σ2 and σ4 domains are interspersed by domains with a high degree of disorder. These findings suggest that E binding induces major changes in both the folding and domain arrangement of σS and provide insights into the possible mechanisms of regulation of σS activity by its chaperone Crl.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Salmonella typhimurium
/
Fator sigma
/
Proteínas de Bactérias
/
Proteínas Recombinantes de Fusão
/
Regulação Bacteriana da Expressão Gênica
/
Holoenzimas
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article