Backtracking behavior in viral RNA-dependent RNA polymerase provides the basis for a second initiation site.
Nucleic Acids Res
; 43(21): 10421-9, 2015 Dec 02.
Article
em En
| MEDLINE
| ID: mdl-26496948
ABSTRACT
Transcription in RNA viruses is highly dynamic, with a variety of pauses interrupting nucleotide addition by RNA-dependent RNA polymerase (RdRp). For example, rare but lengthy pauses (>20 s) have been linked to backtracking for viral single-subunit RdRps. However, while such backtracking has been well characterized for multi-subunit RNA polymerases (RNAPs) from bacteria and yeast, little is known about the details of viral RdRp backtracking and its biological roles. Using high-throughput magnetic tweezers, we quantify the backtracking by RdRp from the double-stranded (ds) RNA bacteriophage Φ6, a model system for RdRps. We characterize the probability of entering long backtracks as a function of force and propose a model in which the bias toward backtracking is determined by the base paring at the dsRNA fork. We further discover that extensive backtracking provides access to a new 3'-end that allows for the de novo initiation of a second RdRp. This previously unidentified behavior provides a new mechanism for rapid RNA synthesis using coupled RdRps and hints at a possible regulatory pathway for gene expression during viral RNA transcription.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
RNA Polimerase Dependente de RNA
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Bacteriófago phi 6
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Sítio de Iniciação de Transcrição
Idioma:
En
Revista:
Nucleic Acids Res
Ano de publicação:
2015
Tipo de documento:
Article