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Bidirectional DNA unwinding by a ternary complex of T antigen, nucleolin and topoisomerase I
Author(s) -
Seinsoth Stephanie,
UhlmannSchiffler Heike,
Stahl Hans
Publication year - 2003
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.embor770
Subject(s) - nucleolin , biology , helicase , microbiology and biotechnology , dna replication , replication factor c , eukaryotic dna replication , dna , genetics , gene , cytoplasm , rna , nucleolus
The simian virus 40 large tumour‐antigen (T antigen) DNA helicase is a hexameric structure; it has been proposed that, in viral DNA replication, two of these hexamers are combined to form a bipartite holoenzyme that acts concurrently at both forks of a replication bubble. In a search for structural components of this helicase complex, we have identified nucleolin as a specific binding protein for the T‐antigen hexamer. We show that nucleolin, in co‐operation with human topoisomerase I, mediates the cohesion of the T‐antigen helicase holoenzyme during plasmid unwinding. Our results provide biochemical evidence for a direct role of nucleolin in DNA replication, in addition to its known function in ribosome biogenesis. The data presented here suggest that nucleolin enables the formation of a functional ‘helicase‐swivelase’ complex at the replication fork.