A 7-kDa region of the bacteriophage T7 gene 4 protein is required for primase but not for helicase activity.

AUTOR(ES)

Bernstein, J A

RESUMO

Bacteriophage T7 gene 4 protein, purified from phage-infected cells, consists of a mixture of 56- and 63-kDa species that provides helicase and primase activities required for T7 DNA replication. The 56-kDa species has been purified independently of the colinear 63-kDa species. Like a mixture of the two proteins, the 56-kDa protein binds single-stranded DNA in the presence of dTTP, catalyzes DNA-dependent hydrolysis of dTTP, and has helicase activity. In contrast to the mixture, the 56-kDa protein cannot catalyze template-dependent RNA primer synthesis. In the absence of a DNA template, both the 56-kDa protein and the mixture of the two species synthesize low levels of diribonucleotide. A putative "zinc finger" present near the amino terminus of the 63-kDa protein but absent from the 56-kDa protein may play a major role in the recognition of primase sites in the template.

Documentos Relacionados

• An N-terminal fragment of the gene 4 helicase/primase of bacteriophage T7 retains primase activity in the absence of helicase activity
• Interaction of adjacent primase domains within the hexameric gene 4 helicase-primase of bacteriophage T7
• T7 Single Strand DNA Binding Protein but Not T7 Helicase Is Required for DNA Double Strand Break Repair
• Roles of bacteriophage T7 gene 4 proteins in providing primase and helicase functions in vivo.
• Characterization and crystallization of the helicase domain of bacteriophage T7 gene 4 protein.