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Mol. Cell. Biol., Mar 1995, 1716-1724, Vol 15, No. 3
A Bruckner, F Stadlbauer, LA Guarino, A Brunahl, C Schneider, C Rehfuess, C Previes, E Fanning and HP Nasheuer
Mouse cell extracts support vigorous replication of polyomavirus (Py) DNA
in vitro, while human cell extracts do not. However, the addition of
purified mouse DNA polymerase alpha-primase to human cell extracts renders
them permissive for Py DNA replication, suggesting that mouse polymerase
alpha-primase determines the species specificity of Py DNA replication. We
set out to identify the subunit of mouse polymerase alpha-primase that
mediates this species specificity. To this end, we cloned and expressed
cDNAs encoding all four subunits of mouse and human polymerase
alpha-primase. Purified recombinant mouse polymerase alpha-primase and a
hybrid DNA polymerase alpha-primase complex composed of human subunits p180
and p68 and mouse subunits p58 and p48 supported Py DNA replication in
human cell extracts depleted of polymerase alpha-primase, suggesting that
the primase heterodimer or one of its subunits controls host specificity.
To determine whether both mouse primase subunits were required, recombinant
hybrid polymerase alpha-primases containing only one mouse primase subunit,
p48 or p58, together with three human subunits, were assayed for Py
replication activity. Only the hybrid containing mouse p48 efficiently
replicated Py DNA in depleted human cell extracts. Moreover, in a purified
initiation assay containing Py T antigen, replication protein A (RP-A) and
topoisomerase I, only the hybrid polymerase alpha-primase containing the
mouse p48 subunit initiated primer synthesis on Py origin DNA. Together,
these results indicate that the p48 subunit is primarily responsible for
the species specificity of Py DNA replication in vitro.(ABSTRACT TRUNCATED
AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
The mouse DNA polymerase alpha-primase subunit p48 mediates species- specific replication of polyomavirus DNA in vitro
Institute for Biochemistry, Munich, Germany.
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