PMID:11580240
| Citation |
Jones, JM and Nakai, H (2001) Escherichia coli PriA helicase: fork binding orients the helicase to unwind the lagging strand side of arrested replication forks. J. Mol. Biol. 312:935-47 |
|---|---|
| Abstract |
Escherichia coli PriA is a primosome assembly protein with 3' to 5' helicase activity whose apparent function is to promote resumption of DNA synthesis following replication-fork arrest. Here, we describe how initiation of helicase activity on DNA forks is influenced by both fork structure and by single-strand DNA-binding protein. PriA could recognize and unwind forked substrates where one or both arms were primarily duplex, and PriA required a small (two bases or larger) single-stranded gap at the fork in order to initiate unwinding. The helicase was most active on substrates with a duplex lagging-strand arm and a single-stranded leading-strand arm. On this substrate, PriA was capable of translocating on either the leading or lagging strands to unwind the duplex ahead of the fork or the lagging-strand duplex, respectively. Fork-specific binding apparently orients the helicase domain to unwind the lagging-strand duplex. Binding of single-strand-binding protein to forked templates could inhibit unwinding of the duplex ahead of the fork but not unwinding of the lagging-strand duplex or translocation on the lagging-strand template. While single-strand-binding protein could inhibit binding of PriA to the minimal, unforked DNA substrates, it could not inhibit PriA binding to forked substrates. In the cell, single-strand-binding protein and fork structure may direct PriA helicase to translocate along the lagging-strand template of forked structures such that the primosome is specifically assembled on that DNA strand. |
| Links |
PubMed Online version:10.1006/jmbi.2001.4930 |
| Keywords |
Base Sequence; DNA Helicases/metabolism; DNA Primers; DNA Replication; DNA, Single-Stranded/chemistry; DNA, Single-Stranded/genetics; DNA, Single-Stranded/metabolism; DNA-Binding Proteins/deficiency; DNA-Binding Proteins/genetics; DNA-Binding Proteins/metabolism; Escherichia coli/enzymology; Escherichia coli/genetics; Models, Biological; Molecular Sequence Data; Nucleic Acid Conformation; Protein Binding; Replication Protein A; Substrate Specificity; Templates, Genetic |
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