| Autor: |
Niedziela-Majka A; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110-1093., Chesnik MA; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110-1093., Tomko EJ; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110-1093., Lohman TM; Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri 63110-1093. Electronic address: lohman@biochem.wustl.edu. |
| Jazyk: |
angličtina |
| Zdroj: |
The Journal of biological chemistry [J Biol Chem] 2007 Sep 14; Vol. 282 (37), pp. 27076-27085. Date of Electronic Publication: 2007 Jul 12. |
| DOI: |
10.1074/jbc.M704399200 |
| Abstrakt: |
Structural studies of the Bacillus stearothermophilus PcrA protein along with biochemical studies of the single-stranded (ss) DNA translocation activity of PcrA monomers have led to the suggestion that a PcrA monomer possesses processive helicase activity in vitro. Yet definitive studies testing whether the PcrA monomer possesses processive helicase activity have not been performed. Here we show, using single turnover kinetic methods, that monomers of PcrA are able to translocate along ssDNA, in the 3' to 5' direction, rapidly and processively, whereas these same monomers display no detectable helicase activity under the same solution conditions in vitro. The PcrA monomer ssDNA translocation activity, although necessary, is not sufficient for processive helicase activity, and thus the translocase and helicase activities of PcrA are separable. These results also suggest that the helicase activity of PcrA needs to be activated either by self-assembly or through interactions with accessory proteins. This same behavior is displayed by both the Escherichia coli Rep and UvrD monomers. Hence, all three of these SF1 enzymes are ssDNA translocases as monomers but do not display processive helicase activity in vitro unless activated. The fact that the translocase and helicase activities are separable suggests that each activity may be used for different functions in vivo. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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