Abstract
Replication of satellite phage P4 of Escherichia coli is dependent on three phage-encoded elements: the origin (ori), a cis replication element (crr), and the product of the alpha gene, gp alpha. In P4 replication is origin-specific resulting in monomeric form I DNA. DNA synthesis requires chromosomally encoded proteins DNA polymerase III holoenzyme, SSB, DNA gyrase and probably topoisomerase I; host-encoded initiation and priming functions are dispensable. The alpha protein is multifunctional in P4 replication, combining three activities in a single polypeptide chain. First, the protein complexes specifically with type I repeats at ori and crr. Second, the helicase activity associated with gp alpha unwinds DNA with 3'--> 5' polarity. Third, the primase activity results in the synthesis of RNA primers. Defined sequence motifs in gp alpha correlate with the helicase and primase activities which are arranged in distinct, separable domains. Primase activity is associated with the N-terminal half of the protein, ori/crr binding with the C-terminal portion. A model for the initiation mechanism of P4 replication which resembles that of mammalian simian virus 40 is discussed.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
