Related Experiment Video
Updated: Jun 26, 2026
09:08
Generation and Assembly of Virus-Specific Nucleocapsids of the Respiratory Syncytial Virus
Published on: July 27, 2021
Self-assembly of Epstein-Barr virus capsids
Brandon W Henson1, Edward M Perkins, Jonathan E Cothran
1Viral Oncology Program, The Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, 353 CRB1 Viral Oncology, 1650 New Orleans St., Baltimore, MD 21117, USA.
Journal of Virology
|January 23, 2009
Summary
Epstein-Barr virus (EBV) capsid assembly requires only six proteins, including the small capsid protein BFRF3, which is crucial for structural stability and localization. This study elucidates the essential components and interactions for EBV capsid formation.
Area of Science:
- Virology
- Molecular Biology
- Structural Biology
Background:
- Epstein-Barr virus (EBV), a gammaherpesvirus, infects B lymphocytes and causes lymphoproliferative diseases.
- The molecular mechanisms of EBV capsid assembly and its structural details remain largely uncharacterized.
Purpose of the Study:
- To investigate the minimal protein requirements for EBV capsid assembly.
- To characterize the role of specific capsid proteins, particularly the small capsid protein (BFRF3), in the assembly process.
Main Methods:
- Utilized the baculovirus expression vector system to express six key EBV proteins: BcLF1, BORF1, BDLF1, BFRF3, BdRF1, and BVRF2.
- Employed electron microscopy and sedimentation methods to analyze capsid structures.
- Conducted mutational analysis of the BFRF3 protein.
Main Results:
- Demonstrated that six proteins are sufficient for the assembly of closed EBV capsid structures.
- Identified the EBV small capsid protein (BFRF3) as essential for stable capsid formation.
- Determined that BFRF3 localization to nuclear assembly sites requires major capsid (BcLF1) and scaffold (BdRF1) proteins.
- Mutational analysis revealed that the N-terminal half of BFRF3 (amino acids 1-88) is necessary and sufficient for assembly, with specific regions mediating localization and interaction with BcLF1.
Conclusions:
- EBV capsid assembly, similar to other herpesviruses, can be achieved with six core proteins.
- The small capsid protein BFRF3 plays a multifunctional role, essential for structural integrity and proper localization during assembly.
- Elucidated key interactions and functional domains within BFRF3, providing insights into gammaherpesvirus capsid formation.
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...
00:56Viral Structure
Viruses are extraordinarily diverse in shape and size, but they all have several structural features in common. All viruses have a core that contains a DNA- or RNA-based genome. The core is surrounded by a protective coat of proteins called the capsid. The capsid is composed of subunits called capsomeres. The capsid and genome-containing core are together known as the nucleocapsid.
01:33Coat Assembly and GTPases
Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
01:32Pinching-off of Coated Vesicles
Vesicle budding is orchestrated by distinct cytosolic proteins such as adaptor proteins, coat proteins, and GTPases. To initiate vesicle budding, membrane-bending proteins containing crescent-shaped BAR domains bind to the lipid heads in the bilayer and distort the membrane to form a protein-coated vesicle bud. Adaptors proteins such as AP2 for clathrin-coated vesicles can nucleate on the deformed membrane. Finally, coat proteins such as clathrin or COPI and COPII assemble into a coat forming...
01:45Vesicular Tubular Clusters
After budding out from the ER membrane, some COPII vesicles lose their coat and fuse with one another to form larger vesicles and interconnected tubules called vesicular tubular clusters or VTCs. These clusters constitute a compartment at the ER-Golgi interface known as ERGIC (Endoplasmic Reticulum Golgi Intermediate Compartment). The ERGIC is a mobile membrane-bound cargo transport system that sorts proteins secreted from ER and delivers them to the Golgi.
With the help of motor proteins such...
With the help of motor proteins such...
01:38Intralumenal Vesicles and Multivesicular Bodies
Intraluminal vesicles (ILVs) are small vesicles 50-80 nm in diameter formed during the maturation of early endosomes. A specialized endosome containing numerous ILVs is called a multivesicular body (MVB). ILVs contain internalized molecules such as antigens, nucleic acids, proteins, and metabolites. Some of these molecules are released from the MVBs inside exosomes and are transported to other cells. Other MVBs contain molecules that are retained in the ILVs and are later degraded within the...