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Bacterial RNA Polymerase

Bacterial RNA Polymerase

Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...

Bacterial RNA Polymerase

Bacterial RNA Polymerase

Unlike eukaryotes, bacteria use a single RNA Polymerase (RNAP) to transcribe all genes. The different subunits of bacterial RNAPhave distinct functions. The multisubunit structure of the bacterial RNAP helps the enzyme to maintain catalytic function, facilitate assembly, interact with DNA and RNA, and self-regulate its activity.
In most genes, the transcription site is a single base present upstream of the coding sequence. Though RNAP is a catalytically efficient enzyme, it does not recognize...

Eukaryotic RNA Polymerases

Eukaryotic RNA Polymerases

RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...

Eukaryotic RNA Polymerases

Eukaryotic RNA Polymerases

RNA Polymerase (RNAP) is conserved in all animals, with bacterial, archaeal, and eukaryotic RNAPs sharing significant sequence, structural, and functional similarities. Among the three eukaryotic RNAPs, RNA Polymerase II is most similar to bacterial RNAP in terms of both structural organization and folding topologies of the enzyme subunits. However, these similarities are not reflected in their mechanism of action.
All three eukaryotic RNAPs require specific transcription factors, of which the...

Transcription Initiation

Transcription Initiation

Initiation is the first step of transcription in eukaryotes. Prokaryotic RNA Polymerase (RNAP) can bind to the template DNA and start transcribing. On the other hand, transcription in eukaryotes requires additional proteins, called transcription factors, to first bind to the promoter region in the DNA template. This binding helps recruit the specific RNAP that can assemble on the DNA and start transcription.
The promoters and enhancers and their accessory proteins allow tight regulation of...

The Replisome

The Replisome

DNA replication is carried out by a large complex of proteins that act in a coordinated matter to achieve high-fidelity DNA replication. Together this complex is known as the DNA replication machinery or the replisome.
The synthesis of the leading and lagging strands is a highly coordinated process. To explain this, the “Trombone model” was proposed by Bruce Alberts in 1980. The DNA loop formation starts when a primer is synthesized on the parent lagging strand. The loop grows with the...

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Related Experiment Video

Updated: May 25, 2026

Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase

Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase

Published on: April 29, 2010

Molecular basis for RNA polymerization by Qβ replicase.

Daijiro Takeshita¹, Kozo Tomita

¹Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan.

Nature Structural & Molecular Biology

|January 17, 2012

Summary

Host proteins EF-Tu and EF-Ts are crucial for Qβ replicase function. EF-Tu modulates RNA elongation by forming a template exit channel and splitting double-stranded RNA during viral RNA synthesis.

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Chemical Triphosphorylation of Oligonucleotides

Chemical Triphosphorylation of Oligonucleotides

Published on: June 2, 2022

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Last Updated: May 25, 2026

Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase

Direct Restart of a Replication Fork Stalled by a Head-On RNA Polymerase

Published on: April 29, 2010

Chemical Triphosphorylation of Oligonucleotides

Chemical Triphosphorylation of Oligonucleotides

Published on: June 2, 2022

Area of Science:

Molecular Biology
Virology
Structural Biology

Background:

Core Qβ replicase is a complex of viral RNA-dependent RNA polymerase (β-subunit) and host Escherichia coli translational elongation factors EF-Tu and EF-Ts.
The precise roles of EF-Tu and EF-Ts within the viral replicase complex remain largely undefined.

Purpose of the Study:

To elucidate the functional roles of host translational elongation factors EF-Tu and EF-Ts in the Qβ viral RNA replication process.
To understand the structural mechanisms by which EF-Tu contributes to RNA polymerization by Qβ replicase.

Main Methods:

Structural analyses of core Qβ replicase during RNA polymerization.
Investigating the interactions between the β-subunit and EF-Tu at different stages of RNA synthesis.

Main Results:

The 3'-adenine of template RNA serves as a stable platform for de novo initiation of RNA synthesis.
EF-Tu collaborates with the β-subunit to form a template exit channel essential for RNA elongation.
EF-Tu facilitates the splitting of temporarily double-stranded RNA, enabling template translocation during elongation.

Conclusions:

EF-Tu plays a critical, non-canonical role in Qβ viral RNA elongation, distinct from its function in protein synthesis.
The structural insights reveal how host factors are repurposed to support viral replication machinery.