DnaB drives DNA branch migration and dislodges proteins while encircling two DNA strands.
DnaB is a ring-shaped, hexameric helicase that unwinds the E. coli DNA replication fork while encircling one DNA strand. This report demonstrates that DnaB can also encircle both DNA strands and then actively translocate along the duplex. With two strands positioned inside its central channel, DnaB translocates with sufficient force to displace proteins tightly bound to DNA with no resultant DNA unwinding. Thus, DnaB may clear proteins from chromosomal DNA. Furthermore, while encircling two DNA strands, DnaB can drive branch migration of a synthetic Holliday junction with heterologous duplex arms, suggesting that DnaB may be directly involved in DNA recombination in vivo. DnaB binds to just one DNA strand during branch migration. T7 phage gp4 protein also drives DNA branch migration, suggesting this activity generalizes to other ring-shaped helicases.
Kaplan
Daniel L
DL
Laboratory of DNA Replication, Rockefeller University, New York, NY 10021, USA. dkaplan@mod.rockefeller.edu
O'Donnell
Mike
M
D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins; D004265:DNA Helicases / Q000378:metabolism*; D004261:DNA Replication; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D053488:DnaB Helicases; D029968:Escherichia coli Proteins / Q000378:metabolism*; D005026:Ethylene Glycols / Q000378:metabolism; D009690:Nucleic Acid Conformation; D011995:Recombination, Genetic
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D005026:Ethylene Glycols; C077067:hexaethylene glycol; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C506730:dnaB protein, E coli; D004265:DNA Helicases; D053488:DnaB Helicases