Sequence independent duplex DNA opening reaction catalysed by SV40 large tumor antigen. |
| |
Authors: | M Scheffner R Wessel and H Stahl |
| |
Affiliation: | Fakult?t für Biologie, Universit?t Konstanz, FRG. |
| |
Abstract: | Simian virus 40 (SV40) large tumor antigen (T antigen) is mainly localized in the nucleus where it exhibits two biochemical properties: DNA binding and helicase activity. Both activities are necessary for viral DNA replication and may also enable T antigen to modulate cellular growth. Here we present biochemical and electron microscopic evidence that the helicase activity can start at internal sites of fully double-stranded DNA molecules not containing the SV40 origin or replication. Using T antigen specific monoclonal antibodies, this unwinding reaction can be biochemically divided in an initiation (duplex opening) and a propagation step. The duplex opening reaction (as well as the propagation step) does not depend on a specific DNA sequence or secondary structure. In addition, we have found that T antigen forms an ATP dependent nucleoprotein complex at double-stranded DNA, which may be an essential step for the sequence independent duplex DNA opening reaction. |
| |
Keywords: | |
|
|