Open AccessBacteriophage P4 DNA replication
Author(s) -
Ziegelin Günter,
Lanka Erich
Publication year - 1995
Publication title -
fems microbiology reviews
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.91
H-Index - 212
eISSN - 1574-6976
pISSN - 0168-6445
DOI - 10.1111/j.1574-6976.1995.tb00191.x
Subject(s) - biology , bacteriophage , replication (statistics) , dna replication , genetics , dna , computational biology , evolutionary biology , virology , gene , escherichia coli
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 α gene, gpα. In vitro 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 α 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 gpα unwinds DNA with 3′→ 5′ polarity. Third, the primase activity results in the synthesis of RNA primers. Defined sequence motifs in gpα 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.