Structural basis of Q-dependent antitermination.
Proc Natl Acad Sci U S A
; 116(37): 18384-18390, 2019 09 10.
Article
em En
| MEDLINE
| ID: mdl-31455742
ABSTRACT
Lambdoid bacteriophage Q protein mediates the switch from middle to late bacteriophage gene expression by enabling RNA polymerase (RNAP) to read through transcription terminators preceding bacteriophage late genes. Q loads onto RNAP engaged in promoter-proximal pausing at a Q binding element (QBE) and adjacent sigma-dependent pause element (SDPE) to yield a Q-loading complex, and Q subsequently translocates with RNAP as a pausing-deficient, termination-deficient Q-loaded complex. Here, we report high-resolution structures of 4 states on the pathway of antitermination by Q from bacteriophage 21 (Q21) Q21, the Q21-QBE complex, the Q21-loading complex, and the Q21-loaded complex. The results show that Q21 forms a torus, a "nozzle," that narrows and extends the RNAP RNA-exit channel, extruding topologically linked single-stranded RNA and preventing the formation of pause and terminator hairpins.
Palavras-chave
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Proteínas Virais
/
RNA Polimerases Dirigidas por DNA
Tipo de estudo:
Prognostic_studies
Idioma:
En
Ano de publicação:
2019
Tipo de documento:
Article