Integration host factor interacts with the DNA replication enhancer of filamentous phage f1

D. Greenstein, N. D. Zinder, K. Horiuchi

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

We present data which show that the Escherichia coli integration host factor (IHF) is an activator of phage f1 DNA replication. Phage f1 poorly infects bacterial strains lacking IHF because IHF is required for efficient expression of F-pili, the receptor for f1 phage. However, when F- strains are transfected with f1 DNA the phage replicates in IHF mutants (himA, himD, or himA himD) at a rate of only 3% of that in wild-type bacteria. A plasmid dependent on the f1 replicon fails to transform IHF mutants. By gel retardation analysis, we show that IHF specifically binds to the origin of replication. DNase I 'footprinting' experiments demonstrate that IHF binds to multiple sites within the replication enhancer sequence, a cis-acting, A+T-rich sequence that potentiates f1 DNA replication. Moreover, the effect of IHF mutation on f1 growth is suppressed by initiator protein (f1 gene II) mutations that restore efficient replication from origins that lack a functional replication enhancer sequence. This genetic evidence supports the conclusion that the replication enhancer sequence is the site of action of IHF.

Original languageEnglish (US)
Pages (from-to)6262-6266
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume85
Issue number17
DOIs
StatePublished - 1988

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