Displacement of a DNA binding protein by Dda helicase

Displacement of a DNA binding protein by Dda helicase

Bacteriophage T4 Dda helicase has recently been shown to be active as a monomer for unwinding of short duplex oligonucleotides and for displacing streptavidin from 3'-biotinylated oligonucleotides. However, its activity for streptavidin displacement and DNA unwinding has been shown to increase as the number of Dda molecules bound to the substrate molecule increases. A substrate was designed to ...

Simultaneous binding to the tracking strand, displaced strand and the duplex of a DNA fork enhances unwinding by Dda helicase

Interactions between helicases and the tracking strand of a DNA substrate are well-characterized; however, the role of the displaced strand is a less understood characteristic of DNA unwinding. Dda helicase exhibited greater processivity when unwinding a DNA fork compared to a ss/ds DNA junction substrate. The lag phase in the unwinding progress curve was reduced for the forked DNA compared to ...

Pre-steady-state DNA unwinding by bacteriophage T4 Dda helicase reveals a monomeric molecular motor.

Helicases are molecular motor enzymes that unwind and translocate nucleic acids. One of the central questions regarding helicase activity is whether the process of coupling ATP hydrolysis to DNA unwinding requires an oligomeric form of the enzyme. We have applied a pre-steady-state kinetics approach to address this question with the bacteriophage T4 Dda helicase. If a helicase can function as a...

Bypass of a protein barrier by a replicative DNA helicase

Dual functions of single-stranded DNA-binding protein in helicase loading at the bacteriophage T4 DNA replication fork.

Semi-conservative DNA synthesis reactions catalyzed by the bacteriophage T4 DNA polymerase holoenzyme are initiated by a strand displacement mechanism requiring gp32, the T4 single-stranded DNA (ssDNA)-binding protein, to sequester the displaced strand. After initiation, DNA helicase acquisition by the nascent replication fork leads to a dramatic increase in the rate and processivity of leading...