Assembling filamentous phage occlude pIV channels

D. K. Marciano, M. Russel, S. M. Simon

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28 Scopus citations


Filamentous phage f1 is exported from its Escherichia coil host without killing the bacterial cell. Phage-encoded protein pIV, which is required for phage assembly and secretion, forms large highly conductive channels in the outer membrane of E. coli. It has been proposed that the phage are extruded across the bacterial outer membrane through pIV channels. To test this prediction, we developed an in vivo assay by using a mutant pIV that functions in phage export but whose channel opens in the absence of phage extrusion. In E. coil lacking its native maltooligosacharride transporter LamB, this pIV variant allowed oligosaccharide transport across the outer membrane. This entry of oligosaccharide was decreased by phage production and still further decreased by production of phage that cannot be released from the cell surface. Thus, exiting phage block the pIV-dependent entry of oligosaccharide, suggesting that phage occupy the lumen of pIV channels. This study provides the first evidence, to our knowledge, for viral exit through a large aqueous channel.

Original languageEnglish (US)
Pages (from-to)9359-9364
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number16
StatePublished - Jul 31 2001

ASJC Scopus subject areas

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