Related Experiment Video
Updated: May 19, 2026
09:04
Sequence-specific and Selective Recognition of Double-stranded RNAs over Single-stranded RNAs by Chemically Modified Peptide Nucleic Acids
Published on: September 21, 2017
PCNA structure and function: insights from structures of PCNA complexes and post-translationally modified PCNA.
Lynne M Dieckman1, Bret D Freudenthal, M Todd Washington
1Department of Biochemistry, University of Iowa College of Medicine, Iowa City, IA, 52242-1109, USA.
Sub-Cellular Biochemistry
|August 25, 2012
Summary
Proliferating cell nuclear antigen (PCNA) is a DNA sliding clamp essential for replication, repair, and recombination. Structural studies reveal how PCNA interacts with proteins and how modifications alter its function.
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Proliferating cell nuclear antigen (PCNA) functions as a eukaryotic DNA sliding clamp, forming a homotrimer that encircles DNA.
- PCNA enhances the processivity of replicative DNA polymerases and serves as a platform for recruiting proteins involved in DNA metabolism.
- Understanding PCNA's interactions is crucial for comprehending DNA replication, repair, and recombination mechanisms.
Purpose of the Study:
- To elucidate the structural basis of PCNA's interactions with its binding partners.
- To investigate the impact of post-translational modifications (ubiquitination and SUMOylation) on PCNA function and binding specificity.
- To provide insights into the dynamic role of PCNA at replication forks.
Main Methods:
- X-ray crystallography was employed to determine the structures of PCNA in complex with various binding proteins.
- Structural analysis of ubiquitin-modified and SUMO-modified PCNA complexes.
- Comparative structural analysis to understand altered binding specificities due to post-translational modifications.
Main Results:
- X-ray structures revealed how PCNA recognizes and recruits specific proteins to replication forks.
- Structures of modified PCNA demonstrated how ubiquitination and SUMOylation modulate PCNA's interactions with partner proteins.
- Insights into the structural mechanisms underlying PCNA's versatile roles in DNA processing.
Conclusions:
- Structural studies of PCNA complexes provide fundamental insights into DNA replication, repair, and recombination.
- Post-translational modifications significantly alter PCNA's interaction landscape, fine-tuning its functions.
- PCNA's structural plasticity is key to its central role in maintaining genome stability.
Related Concept Videos
02:41Protein Complex Assembly
Proteins can form homomeric complexes with another unit of the same protein or heteromeric complexes with different types. Most protein complexes self-assemble spontaneously via ordered pathways, while some proteins need assembly factors that guide their proper assembly. Despite the crowded intracellular environment, proteins usually interact with their correct partners and form functional complexes.
Many viruses self-assemble into a fully functional unit using the infected host cell to...
Many viruses self-assemble into a fully functional unit using the infected host cell to...
02:04Covalently Linked Protein Regulators
Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.
These groups modify specific amino acids in a protein.
01:24Protein Organization
Proteins are polymers of amino acid residues. They are versatile and responsible for different cellular functions, including DNA replication, molecular transport, catalysis, and structural support. Proteins have a hierarchical structure comprising at least three levels of organization: primary, secondary, and tertiary structure. Some large proteins have a quaternary structure where individual protein subunits are linked together.
The primary structure of a protein is its amino acid sequence.
The primary structure of a protein is its amino acid sequence.
01:13Protein Organization
Overview
01:25Nucleic Acid Structure
The pentose sugar in DNA is deoxyribose, while in RNA the pentose sugar is ribose. The difference between the sugars is the presence of the hydroxyl group on the ribose's second carbon and a hydrogen on the deoxyribose's second carbon. The phosphate residue attaches to the hydroxyl group of the 5′ carbon of one sugar and the hydroxyl group of the 3′ carbon of the sugar of the next nucleotide, which forms a 5′ to 3′ phosphodiester linkage.
DNA Structure
DNA has a double-helix structure. The...
DNA Structure
DNA has a double-helix structure. The...
02:15Protein and Protein Structure
Proteins are one of the most abundant organic molecules in living systems and have the most diverse range of functions of all macromolecules. Proteins may be structural, regulatory, contractile, or protective. They may serve in transport, storage, or membranes; or they may be toxins or enzymes. Their structures, like their functions, vary greatly. They are all, however, amino acid polymers arranged in a linear sequence.
A protein's shape is critical to its function. For example, an enzyme can...
A protein's shape is critical to its function. For example, an enzyme can...