A single stranded DNA binding protein isolated from HeLa cells facilitates Ni2+ activation of DNA polymerases in vitro.
Biochemistry
; 33(50): 15141-8, 1994 Dec 20.
Article
en En
| MEDLINE
| ID: mdl-7999774
The divalent nickel ion (Ni2+) is one of several metal ions that can substitute for Mg2+ in the activation of DNA polymerases in vitro, but usually with very low efficiency. We have purified and partially characterized a Ni(2+)-binding protein (p40) from HeLa cell extracts that can specifically enhance the polymerase activity of DNA polymerase alpha (pol alpha) and other DNA polymerases in response to Ni2+. This protein, with a molecular mass of 40 kDa, is a single stranded DNA binding protein that binds to a M13 DNA template-primer with an optimum stoichiometry of approximately 90 equiv of protein per equiv of DNA template and enhances the affinity of pol alpha for the primer-template. In the presence of Ni2+, p40 exhibits an increased affinity for DNA. The p40 increased by 3- to 6-fold the rates at which pol alpha and the Klenow fragment of Escherichia coli DNA polymerase I (KF) replicate different DNA templates in response to Ni2+. The low processivity of Ni(2+)-activated pol on primed M13 ssDNA was also enhanced by the presence of p40. The rates of Ni(2+)-dependent replication by inherently more processive enzymes, DNA polymerase delta and T4 DNA polymerase, were not significantly increased by p40 when M13 ssDNA was used as a template; however, p40 did increase the activity of T4 polymerase on an activated calf thymus DNA template. The protein did not stimulate Mg(2+)-activated DNA replication.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Células HeLa
/
Proteínas de Unión al ADN
/
ADN Polimerasa Dirigida por ADN
/
Níquel
Límite:
Humans
Idioma:
En
Revista:
Biochemistry
Año:
1994
Tipo del documento:
Article
Pais de publicación:
Estados Unidos