The mechanism for producing two symmetries at the head-tail junction of bacteriophages: a hypothesis

Research output: Contribution to journalArticle

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Abstract

Some double-stranded DNA bacteriophages consist of DNA packaged in a proteinaceous capsid. The capsid has a DNA-enclosing outer shell (head) attached to an external projection (tail). At the head-tail junction is a ring of subunits (connector) that has either six or twelve-fold rotational symmetry, and is joined to the head at an axis of the head's five-fold rotational symmetry. The head is made of subunits in either an icosahedral array or an array consisting of two icosahedral hemispheres separated by a cylinder of subunits. During infection of a host, the head with connector is assembled as a procapsid that subsequently packages DNA and joins a tail. The mechanism for producing two symmetries at the head-tail junction has in the past been an unsolved problem. The observation that the connector of bacteriophage T7 does not nucleate asembly of the outer shell of T7's icosahedral procapsid (P. Serwer and R. H. Watson [1982] J. Virol. 42, 595-601) places a constraint on a solution for the above problem. To solve the above problem for icosahedral procapsids, it is proposed here that: (a) assembly of the outer shell of procapsids is nucleated by a six-membered ring of hexameric aggregates of the major outer shell protein, (b) the connector is assembled in the center of this ring, (c) one of the hexamers dissociates from the ring, creating a five-membered ring and forcing the connector to the inside of the outer shell. A related mechanism is proposed for nucleation of the elongated procapsid of bacteriophage T4.

Original languageEnglish (US)
Pages (from-to)155-161
Number of pages7
JournalJournal of Theoretical Biology
Volume127
Issue number2
DOIs
StatePublished - Jul 21 1987

Fingerprint

Bacteriophages
Connector
bacteriophages
Tail
Shell
DNA
tail
Head
Ring
Symmetry
Rotational symmetry
capsid
Capsid
Fold
Hemisphere
Nucleation
Bacteriophage T7
Forcing
Join
Bacteriophage T4

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)
  • Applied Mathematics
  • Modeling and Simulation
  • Statistics and Probability
  • Medicine(all)

Cite this

The mechanism for producing two symmetries at the head-tail junction of bacteriophages : a hypothesis. / Serwer, Philip.

In: Journal of Theoretical Biology, Vol. 127, No. 2, 21.07.1987, p. 155-161.

Research output: Contribution to journalArticle

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