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Inhibition of heterologous DNA replication by the MVMp nonstructural NS-1 protein: identification of a target
L Tenenbaum1, F Dupont, P Spegelaere
1Department of Molecular Biology, Université Libre de Bruxelles, Rhode Saint Genèse, Belgium.
Abstract:
The nonstructural protein NS-1 of minute virus of mice (MVMp), an autonomous parvovirus, trans-inhibits the replication of a chimeric plasmid containing the SV40 origin of replication (ori) embedded in the MVMp genome. It appears that a 157-bp 5' proximal sequence of MVMp DNA is sufficient, in the presence of NS-1, to cause the inhibition of DNA replication driven by the SV40 ori placed on the same molecule. This effect is not dependent on the orientation of the MVMp target sequence and results from both a reduced level of utilization of SV40 ori and the blockage of progressing replication forks at the level of the target. Furthermore, replication driven by Epstein-Barr virus origin (oriP) is trans-inhibited by MVMp but this inhibition does not require the presence of parvoviral sequences in cis. On the basis of sequence homologies between EBV oriP and MVMp 5' terminal sequence, it is proposed that the direct or indirect interaction of NS-1 with parvovirus-like sequences present in heterologous viral and possibly also cellular genomes may result in an inhibition of DNA replication.
Insights
Minute virus of mice nonstructural protein NS-1 (NS-1) inhibits DNA replication by targeting specific DNA sequences. This parvovirus protein affects both SV40 and Epstein-Barr virus origins of replication.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Minute virus of mice (MVMp) is an autonomous parvovirus.
- The nonstructural protein NS-1 plays a key role in viral replication.
- Parvoviruses exhibit unique replication mechanisms.
Purpose of the Study:
- To investigate the inhibitory effect of MVMp NS-1 on heterologous DNA replication.
- To identify the MVMp DNA sequences involved in replication inhibition.
- To explore the mechanism of NS-1 mediated trans-inhibition.
Main Methods:
- Construction of chimeric plasmids containing MVMp sequences and origins of replication (SV40 ori, EBV oriP).
- Transfection of plasmids into cells and analysis of DNA replication.
- Assessment of replication fork progression and origin utilization.
Main Results:
- MVMp NS-1 trans-inhibited replication from SV40 ori in a chimeric plasmid.
- A 157-bp MVMp 5' proximal sequence was sufficient for NS-1 mediated inhibition.
- Inhibition involved reduced SV40 ori utilization and blocked replication forks.
- Replication from EBV oriP was also trans-inhibited by MVMp, independent of cis-acting parvoviral sequences.
Conclusions:
- MVMp NS-1 can inhibit heterologous DNA replication origins.
- Parvovirus-like sequences in other viral or cellular genomes may be targets for NS-1.
- NS-1 interaction with these sequences can lead to replication inhibition.