Denaturation of the simian virus 40 origin of replication mediated by human replication protein A.
Denaturation of the simian virus 40 origin of replication mediated by human replication protein A.
复制标题
由人类复制蛋白 A 介导的猿猴病毒 40 复制起点的变性。
DOI：
10.1128/mcb.17.7.3876
复制
发表时间：
1997
影响因子：
5.3
通讯作者：
Borowiec,JA
中科院分区：
文献类型：
--
作者：
Iftode,C;Borowiec,JA
The initiation of simian virus 40 (SV40) replication requires recognition of the viral origin of replication (ori) by SV40 T antigen, followed by denaturation oforiin a reaction dependent upon human replication protein A (hRPA). To understand how origin denaturation is achieved, we constructed a 48-bp SV40 “pseudo-origin” with a central 8-nucleotide (nt) bubble flanked by viral sequences, mimicking a DNA structure found within the SV40 T antigen-oricomplex. hRPA bound the pseudo-origin with similar stoichiometry and an approximately fivefold reduced affinity compared to the binding of a 48-nt single-stranded DNA molecule. The presence of hRPA not only distorted the duplex DNA flanking the bubble but also resulted in denaturation of the pseudo-origin substrate in an ATP-independent reaction. Pseudo-origin denaturation occurred in 7 mM MgCl2, distinguishing this reaction from Mg2+-independent DNA-unwinding activities previously reported for hRPA. Tests of other single-stranded DNA-binding proteins (SSBs) revealed that pseudo-origin binding correlates with the known ability of these SSBs to support the T-antigen-dependent origin unwinding activity. Our results suggest that hRPA binding to the T antigen-oricomplex induces the denaturation oforiincluding T-antigen recognition sequences, thus releasing T antigen fromorito unwind the viral DNA. The denaturation activity of hRPA has the potential to play a significant role in other aspects of DNA metabolism, including DNA repair.
