Aphidicolin arrest irreversibly impairs replicating simian virus 40 chromosomes

Area of Science:

• Molecular Biology
• Virology

Background:

• Aphidicolin is a reversible inhibitor of DNA polymerase alpha in vitro.
• SV40 DNA replication relies on DNA polymerase alpha.

Purpose of the Study:

• To investigate the in vivo effects of aphidicolin on SV40 DNA replication.
• To understand the mechanism of aphidicolin-induced inhibition.

Main Methods:

• Exposure of infected cells to aphidicolin.
• Measuring [3H]dT incorporation into viral DNA.
• Analysis of viral DNA maturation using neutral sucrose gradients.
• Comparison of origin-synchronized and ongoing SV40 replicons.

Main Results:

• In vivo aphidicolin exposure caused irreversible inhibition of viral DNA synthesis.
• Replicating SV40 DNA lost maturation ability after drug removal.
• No DNA degradation was observed during short aphidicolin exposure.
• Longer exposure led to breakdown of arrested intermediates and resumed synthesis.
• Ongoing replicons were more affected than origin-synchronized ones.

Conclusions:

• Aphidicolin selectively impairs replicating SV40 chromosomes during arrest.
• This impairment may prevent new replication rounds by occupying nuclear sites.