4ESV

A New Twist on the Translocation Mechanism of Helicases from the Structure of DnaB with its Substrates

Summary for 4ESV

• Entry DOI: 10.2210/pdb4esv/pdb
• Descriptor: 5'-D(P*TP*TP*TP*TP*TP*TP*TP*TP*TP*TP*TP*TP*TP*T)-3', 5'-D(P*TP*TP*TP*TP*TP*TP*TP*TP*TP*TP*TP*TP*T)-3', Replicative helicase, ... (8 entities in total)
• Functional Keywords: reca fold, helicase, hydrolase-dna complex, hydrolase/dna
• Biological source: Geobacillus stearothermophilus; More
• Total number of polymer chains: 14
• Total formula weight: 623320.43

Authors

Itsathitphaisarn, O.,Wing, R.A.,Eliason, W.K.,Wang, J.,Steitz, T.A. (deposition date: 2012-04-23, release date: 2012-10-24, Last modification date: 2024-02-28)

Primary citation

Itsathitphaisarn, O.,Wing, R.A.,Eliason, W.K.,Wang, J.,Steitz, T.A.
The Hexameric Helicase DnaB Adopts a Nonplanar Conformation during Translocation.
Cell(Cambridge,Mass.), 151:267-277, 2012

PubMed Abstract: DNA polymerases can only synthesize nascent DNA from single-stranded DNA (ssDNA) templates. In bacteria, the unwinding of parental duplex DNA is carried out by the replicative DNA helicase (DnaB) that couples NTP hydrolysis to 5' to 3' translocation. The crystal structure of the DnaB hexamer in complex with GDP-AlF(4) and ssDNA reported here reveals that DnaB adopts a closed spiral staircase quaternary structure around an A-form ssDNA with each C-terminal domain coordinating two nucleotides of ssDNA. The structure not only provides structural insights into the translocation mechanism of superfamily IV helicases but also suggests that members of this superfamily employ a translocation mechanism that is distinct from other helicase superfamilies. We propose a hand-over-hand mechanism in which sequential hydrolysis of NTP causes a sequential 5' to 3' movement of the subunits along the helical axis of the staircase, resulting in the unwinding of two nucleotides per subunit.

PubMed: 23022319
DOI: 10.1016/j.cell.2012.09.014

Experimental method

X-RAY DIFFRACTION (3.2 Å)