title: Characterization of the DNA binding domain of bacteriophage lambda O protein.
abstract: The lambda O and P gene products are required for the initiation of lambda DNA replication. In order to study the biochemistry of this process, we have constructed plasmids that carry the lambda O gene, P gene, and half of the O gene coding for the amino-terminal half of the O protein. Each is under the control of the inducible lambda promoter, PL. We have purified these three proteins from induced cells carrying the plasmids. Our results show that the amino-terminal portion of the O protein binds to the lambda origin of replication in a manner similar to the intact lambda O protein, demonstrating that the amino-terminal portion of O protein contains the DNA binding domain. Using chromatographic procedures, we have isolated a complex of lambda O and P proteins with lambda dv DNA. The amino-terminal portion of the O protein does not complex with P protein under the same conditions. This suggests that the specificity of the lambda O protein for P protein resides in the carboxyl-terminal half of the lambda O protein. Our results also show that, while the intact O protein is active in in vitro replication of lambda dv plasmid DNA, the amino-terminal portion of the O protein is inactive and is a competitive inhibitor of the lambda O protein in this reaction. These results confirm previous genetic observations that were interpreted as indicating a bifunctional structure for the lambda O protein with the amino-terminal domain recognizing the lambda origin of replication and the carboxyl-terminal domain interacting with the lambda P protein.
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D010582:Bacteriophage lambda / Q000378:metabolism*; D004261:DNA Replication; D004279:DNA, Viral / Q000096:biosynthesis / Q000378:metabolism*; D010957:Plasmids; D014764:Viral Proteins / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: D001426:Bacterial Proteins; C024013:DNA replication complex protein, Bacteriophage lambda; D004279:DNA, Viral; C027812:O protein, Bacteriophage lambda; D014764:Viral Proteins