A complex between replication factor A (SSB) and DNA helicase stimulates DNA synthesis of DNA polymerase α on double‐stranded DNA

FEBS Letters

Grosse, Frank¹  Zhang, Suisheng¹ 

[1] German Primate Center, Department of Virology and Immunology, Kellnerweg 4, W-3400 Göttingen, Germany

关键词: Calf thymus;    DNA replication;    DNA unwinding;    SSB protein;    Single-stranded DNA-binding protein;    SSB;    single-stranded DNA-binding protein;    ctSSB;    SSB from calf thymus;    dsDNA;    double-stranded DNA;    PAGE;    polyacrylamide gel electrophoresis;    pol-α;    DNA polymerase α;    SDS;    sodium dodecylsulfate;    RF-A;    replication factor A;    RP-A;    replication protein A;   

DOI  :  10.1016/0014-5793(92)80922-4

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A helicase-like DNA unwinding activity was found in highly purified fractions of the calf thymus single-stranded DNA binding protein (ctSSB). also known as replication protein A (RP-A) or replication factor A (RF-A). This activity depended on the hydrolysis of ATP or dATP, and used CTP with a lower efficiency. ctSSB promoted the homologous DNA polymerase α to perform DNA synthesis on double-stranded templates containing replication fork-like structures. The rate and amount of DNA synthesis was found to be dependent on the concentration of ctSSB. At a 10-fold mass excess of ctSSB over double-stranded DNA, products of 200–600 nucleotides in length were obtained. This comprises or even exceeds the length of a eukaryotic Okazaki fragment. The ctSSB-associated DNA helicase activity is most likely a distinct protein rather than an inherent property of SSB, as inferred from titration experiments between SSB and DNA. The association of a helicase with SSB and the stimulatory action of this complex to the DNA polymerase α-catalyzed synthesis of double-stranded DNA suggests a cooperative function of the three enzymatic activities in the process of eukaryotic DNA replication.

【 授权许可】

Unknown