Related Experiment Videos
The herpes simplex virus type 1 origin-binding protein carries out origin specific DNA unwinding and forms stem-loop
A M Makhov1, P E Boehmer, I R Lehman
1Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill 27599-7295, USA.
The EMBO Journal
|April 1, 1996
Summary
Herpes simplex virus type 1 (HSV-1) UL9 protein binds to replication origins, bending DNA. Upon ATP addition, it unwinds DNA, forming stable, partially single-stranded loops essential for viral replication.
Area of Science:
- Virology
- Molecular Biology
- Structural Biology
Background:
- Herpes simplex virus type 1 (HSV-1) replication relies on specific proteins binding to origins of replication.
- The UL9 protein is known to bind HSV-1 origins (oriS and oriL) and possesses DNA helicase and NTPase activity.
Purpose of the Study:
- To investigate the structural mechanism of UL9 protein binding to the HSV-1 oriS replication origin using electron microscopy.
- To elucidate the role of ATP in UL9 protein-DNA interactions and DNA structural changes.
Main Methods:
- Electron microscopy was employed to visualize UL9 protein binding to oriS-containing DNA fragments.
- Experiments were conducted in the presence and absence of ATP.
- Photocrosslinking and addition of E. coli SSB protein were used to stabilize and characterize DNA structures.
Main Results:
- UL9 protein binds specifically to oriS as dimers, inducing significant DNA bending (35-86 degrees).
- In the presence of ATP, UL9 binding is enhanced, leading to the extrusion of DNA stem-loops (hundreds to thousands of base pairs) from the complex.
- These stem-loops contain oriS, exhibit condensed DNA structures, and exist in a partially paired, partially single-stranded state.
Conclusions:
- HSV-1 UL9 protein specifically unwinds DNA at the oriS origin.
- The process forms a stable, four-stranded DNA structure, likely facilitating subsequent viral replication steps like ICP8 binding.