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Dissecting the functional role of PriA protein‐catalysed primosome assembly in Escherichia coli DNA replication
Author(s) -
Zavitz K. H.,
Marians K. J.
Publication year - 1991
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.1991.tb01846.x
Subject(s) - biology , dna replication , minichromosome maintenance , replication factor c , control of chromosome duplication , helicase , plasmid , origin recognition complex , primase , dna , origin of replication , prokaryotic dna replication , eukaryotic dna replication , dnab helicase , dna replication factor cdt1 , pre replication complex , genetics , licensing factor , gene , reverse transcriptase , rna
Summary The multi‐functional PriA protein of Escherichia coli (formerly replication factor Y or protein n′) serves to guide the ordered assembly of the primosome, a mobile multiprotein replication priming/helicase complex. Primosome assembly is essential for bacteriophage ØX174 complementary DNA strand synthesis and ColE1‐type plasmid replication reconstituted in vitro with purified proteins. The biochemical activities of the primosome suggest that it can fulfil the primase/helicase requirement on the lagging‐strand DNA template during cellular DNA replication. However, reconstruction in vitro of DNA replication of small plasmids containing the E. coli origin of DNA replication ( oriC ) does not require the complete complement of primosomal proteins. Thus, the extent to which PriA‐catalysed primosome assembly participates in chromosomal replication has remained unclear. The recent isolation of the genes encoding PriA, PriB (protein n), PriC (protein n″), and DnaT (protein i) has provided the necessary tools for addressing this issue. The phenotype of mutations in these genes, and other results described in this review, suggest that assembly of the primosome catalysed by PriA does in fact contribute at some stage to normal cellular DNA replication. A model for primososme‐catalysed reactivation of a dysfunctional replication fork is discussed.