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Location of filamentous phage minor coat proteins in phage and in infected cells

H Endemann1, P Model

  • 1Rockefeller University, New York, NY 10021, USA.

Journal of Molecular Biology
|July 21, 1995
PubMed

Insights

All minor coat proteins of phage f1 are integral inner membrane proteins before assembly. These proteins, along with major coat proteins, localize to the infected cell membrane, supporting models of phage assembly and extrusion.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Virology

Background:

  • Bacteriophage f1 assembly involves the precise localization of structural and morphogenetic proteins.
  • Understanding protein localization is crucial for elucidating viral assembly mechanisms.

Purpose of the Study:

  • To investigate the membrane localization of minor coat proteins of phage f1 prior to assembly.
  • To determine the associations between minor and major coat proteins in the infected cell membrane.

Main Methods:

  • Cellular fractionation to isolate membrane proteins.
  • Immunological assays using specific antisera against minor coat proteins.
  • Analysis of protein associations in both membrane and dissociated phage.

Main Results:

  • Minor coat proteins (pVI, pVII, pIX) are integral inner membrane proteins in infected cells.
  • pVI and pIII associate with the major coat protein (pVIII) in the membrane, but not as a complex.
  • pIX is accessible on intact phage, while pVI and pVII are not; pIII is exposed on the exterior.
  • Infected cells accumulate significantly more pVII and pIX than are incorporated into phage.

Conclusions:

  • Phage f1 structural and morphogenetic proteins are localized to the infected cell membrane before assembly.
  • Protein associations observed in dissociated phage differ from those in the membrane.
  • The findings support models of phage assembly occurring concurrently with extrusion from the host cell.

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