Specialized nucleoprotein structures at the origin of replication of bacteriophage lambda: complexes with lambda O protein and with lambda O, lambda P, and Escherichia coli DnaB proteins.
The O protein of bacteriophage lambda is required for initiation of DNA replication at the lambda replicative origin designated ori lambda. The binding sites for O protein are four direct repeats, each of which is an inverted repeat. By means of electron microscopy, we have found that phage lambda O protein utilizes these multiple binding sites to form a specific nucleoprotein structure in which the origin DNA is inferred to be folded or wound. The phage lambda O and P proteins and host DnaB protein interact at ori lambda to generate a larger structure than that formed by O protein alone; P and DnaB proteins fail to form any observable complex when O protein is excluded from the reaction mixture. We conclude that the specialized nucleoprotein structure formed by phage lambda O protein and ori lambda provides for localized initiation of DNA replication by serving as the foundation for the assembly of the initial priming structure. Specialized nucleoprotein structures may be a general means to confer exceptional accuracy on DNA transactions requiring extraordinary precision.
Dodson
M
M
Roberts
J
J
McMacken
R
R
Echols
H
H
D001426:Bacterial Proteins / Q000235:genetics*; D010582:Bacteriophage lambda / Q000235:genetics*; D004261:DNA Replication; D004262:DNA Restriction Enzymes; D004926:Escherichia coli / Q000235:genetics*; D008854:Microscopy, Electron; D009698:Nucleoproteins / Q000235:genetics; D010957:Plasmids; D014764:Viral Proteins / Q000235:genetics*; D014779:Virus Replication
D001426:Bacterial Proteins; D009698:Nucleoproteins; D014764:Viral Proteins; D004262:DNA Restriction Enzymes