Related Experiment Video
Updated: Feb 25, 2026
10:45
iCLIP - Transcriptome-wide Mapping of Protein-RNA Interactions with Individual Nucleotide Resolution
Published on: April 30, 2011
59.4K
Structure of the human CTF18-RFC clamp loader bound to PCNA
Giuseppina R Briola1, Mohammad Tehseen1, Amani Al-Amodi1
1Bioscience Program, Division of Biomedical Sciences, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia.
Elife
|February 23, 2026
Summary
The human CTF18-RFC complex, a key DNA clamp loader, interacts with PCNA and the Pol ε polymerase. Structural studies reveal unique features enabling PCNA loading and stimulating DNA synthesis.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Sliding clamps, such as PCNA, are essential for DNA replication fidelity.
- Clamp loaders are required to load these sliding clamps onto DNA.
- CTF18-RFC is an alternative clamp loader interacting with the leading strand polymerase Pol ε.
Purpose of the Study:
- To structurally characterize the human CTF18-RFC complex and its interaction with PCNA.
- To elucidate the mechanism of PCNA loading by CTF18-RFC.
- To understand CTF18-RFC's role in stimulating Pol ε activity.
Main Methods:
- Cryo-electron microscopy (cryo-EM) at 2.9 Å resolution.
- Structural analysis of the CTF18-RFC-PCNA complex.
- Biochemical assays measuring clamp loading and primer synthesis rates.
Main Results:
- CTF18-RFC's regulatory module (Ctf8 and Dcc1) is flexibly tethered to the RFC module.
- A cryo-EM structure reveals the RFC module bound to PCNA in an autoinhibited state.
- The Ctf18 subunit anchors to PCNA via an atypical PIP box and interacts with RFC5 through a novel β-hairpin.
- Deletion of the β-hairpin destabilizes the complex and impairs clamp loading and Pol ε activity.
Conclusions:
- The human CTF18-RFC complex possesses unique structural features for PCNA loading.
- The N-terminal β-hairpin of Ctf18 is crucial for complex stability and function.
- CTF18-RFC plays a vital role in PCNA loading and stimulating leading strand synthesis by Pol ε.
Related Concept Videos
03:01The Replisome
38.7K
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 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...
38.7K
01:12Clathrin Coated Vesicles
9.7K
Clathrin-coated vesicles use endocytosis to transport receptors and lysosomal hydrolases from the Golgi to the lysosome in the late secretory pathway. Clathrin-mediated endocytosis was the first described endocytic process, and Clathrin-coated vesicles remain one of the most well-studied transport vesicles. The molecular machinery that generates clathrin-coated vesicles comprises over 50 proteins that precisely coordinate vesicle formation. Cell surface receptors concentrated in indented sites...
9.7K
02:28Leaky Scanning
5.8K
During most eukaryotic translation processes, the small 40S ribosome subunit scans an mRNA from its 5' end until it encounters the first start AUG codon. The large 60S ribosomal subunit then joins the smaller one to initiate protein synthesis. The location of the translation initiation is largely determined by the nucleotides near the start codon as there may be multiple translation initiation sites present on the mRNA. Marilyn Kozak discovered that the sequence RCCAUGG (where R...
5.8K