N-terminal deletions of the øX174 external scaffolding protein affect the timing and fidelity of assembly

Asako Uchiyama, Peter Heiman, Bentley A. Fane

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


The first α-helices of Microviridae external scaffolding proteins function as coat protein substrate specificity domains. Mutations in this helix can lengthen the lag phase before progeny production. 5′ deletion genes, encoding N-terminal deletion proteins, were constructed on plasmids and in the øX174 genome. Proteins lacking the first seven amino acids were able to rescue a nullD mutant when expressed from a plasmid. However, the lag phase before progeny production was lengthened. The øX174 mutant with the corresponding genomic gene grew very poorly. The molecular basis of the defective phenotype was complex. External scaffolding protein levels were reduced compared to wild-type and most of the viral coat protein in mutant infected cells appears to be siphoned off the assembly pathway. Second-site suppressors of the growth defects were isolated and appear to act via two different mechanisms. One class of suppressors most likely acts by altering mutant external scaffolding protein expression while the second class of suppressors appears to act on the level of protein-protein interactions.

Original languageEnglish (US)
Pages (from-to)303-309
Number of pages7
Issue number2
StatePublished - Apr 10 2009


  • Microviruses
  • Scaffolding proteins
  • Virus assembly
  • øX174

ASJC Scopus subject areas

  • Virology


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