Determinants of Bacteriophage φ{symbol}29 Head Morphology

Kyung H. Choi, Marc C. Morais, Dwight L. Anderson, Michael G. Rossmann

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Bacteriophage φ{symbol}29 requires scaffolding protein to assemble the 450 × 540 Å prolate prohead with T = 3 symmetry end caps. In infections with a temperature-sensitive mutant scaffolding protein, capsids assemble predominantly into 370 Å diameter isometric particles with T = 3 symmetry that lack a head-tail connector. However, a few larger, 430 Å diameter, particles are also assembled. Cryo-electron microscopy shows that these larger particles are icosahedral with T = 4 symmetry. The prolate prohead, as well as the two isometric capsids with T = 3 and T = 4 symmetry, are composed of similar pentamers and differently skewed hexamers. The skewing of the hexamers in the equatorial region of proheads and in the T = 4 isometric particles reflects their different environments. One of the functions of the scaffolding protein, present in the prohead, may be to stabilize skewed hexamers during assembly.

Original languageEnglish (US)
Pages (from-to)1723-1727
Number of pages5
Issue number11
StatePublished - Nov 2006
Externally publishedYes

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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