A Bacterial Chromosome Structuring Protein Binds Overtwisted DNA to Stimulate Type II Topoisomerases and Enable DNA Replication.

Journal Article (Journal Article)

When DNA is unwound during replication, it becomes overtwisted and forms positive supercoils in front of the translocating DNA polymerase. Unless removed or dissipated, this superhelical tension can impede replication elongation. Topoisomerases, including gyrase and topoisomerase IV in bacteria, are required to relax positive supercoils ahead of DNA polymerase but may not be sufficient for replication. Here, we find that GapR, a chromosome structuring protein in Caulobacter crescentus, is required to complete DNA replication. GapR associates in vivo with positively supercoiled chromosomal DNA, and our biochemical and structural studies demonstrate that GapR forms a dimer-of-dimers that fully encircles overtwisted DNA. Further, we show that GapR stimulates gyrase and topo IV to relax positive supercoils, thereby enabling DNA replication. Analogous chromosome structuring proteins that locate to the overtwisted DNA in front of replication forks may be present in other organisms, similarly helping to recruit and stimulate topoisomerases during DNA replication.

Full Text

Duke Authors

Cited Authors

  • Guo, MS; Haakonsen, DL; Zeng, W; Schumacher, MA; Laub, MT

Published Date

  • October 4, 2018

Published In

Volume / Issue

  • 175 / 2

Start / End Page

  • 583 - 597.e23

PubMed ID

  • 30220456

Pubmed Central ID

  • PMC6173638

Electronic International Standard Serial Number (EISSN)

  • 1097-4172

Digital Object Identifier (DOI)

  • 10.1016/j.cell.2018.08.029


  • eng

Conference Location

  • United States