The evolution of genes within genes and the control of DNA replication in microviruses

Sarah M. Doore, Cameron D. Baird, Aaron P. Roznowski, Bentley A Fane

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Single-stranded DNA(ssDNA) viral life cycles must balance double-stranded DNA (dsDNA) and ssDNA biosynthesis. Previously published in vitro results suggest that microvirus C and host cell SSB proteins play antagonistic roles to achieve this balance. To investigate this in vivo, microvirus DNA replication was characterized in cells expressing cloned C or ssb genes, which would presumably alter the C:SSB protein ratios. Representatives of each microvirus clade (X174, G4, and α3) were used in these studies. α3 DNA replication was significantly more complex. Results suggested that the recognized α3 C gene (CS: small) is one of two C genes. A larger 5′ extended gene could be translated from an upstream GTG start codon (CB: big). Wild-type α3 acquired resistance to elevated SSB levels by mutations that exclusively frameshifted the CB reading frame, whereas mutations in the origin of replication conferred resistance to elevated C protein levels. Expression of either the cloned CB or CS gene complemented am(C) mutants, demonstrating functional redundancy. When the CS start codon was eliminated, strains were only viable if an additional amber mutation was placed in gene C and propagated in an informational suppressing host. Thus, CB protein likely reaches toxic levels in the absence of CS translation. This phenomenon may have driven the evolution of the CS gene within the larger C B gene and could constitute a unique mechanism of regulation. Furthermore, cross-complementation data suggested that interactions between the α3 C and other viral proteins have evolved enough specificity to biochemically isolate its DNA replication from G4 and X174.

Original languageEnglish (US)
Pages (from-to)1421-1431
Number of pages11
JournalMolecular Biology and Evolution
Volume31
Issue number6
DOIs
StatePublished - 2014

Fingerprint

Microviridae
Microvirus
gene
Genes
genes
protein
mutation
start codon
Initiator Codon
Protein C
Mutation
proteins
nonsense mutation
replication origin
Reading Frames
single-stranded DNA
Replication Origin
Poisons
Single-Stranded DNA
viral proteins

Keywords

  • DNA replication
  • microvirus
  • overlapping reading frames
  • phiX174

ASJC Scopus subject areas

  • Genetics
  • Molecular Biology
  • Ecology, Evolution, Behavior and Systematics
  • Medicine(all)

Cite this

The evolution of genes within genes and the control of DNA replication in microviruses. / Doore, Sarah M.; Baird, Cameron D.; Roznowski, Aaron P.; Fane, Bentley A.

In: Molecular Biology and Evolution, Vol. 31, No. 6, 2014, p. 1421-1431.

Research output: Contribution to journalArticle

Doore, Sarah M. ; Baird, Cameron D. ; Roznowski, Aaron P. ; Fane, Bentley A. / The evolution of genes within genes and the control of DNA replication in microviruses. In: Molecular Biology and Evolution. 2014 ; Vol. 31, No. 6. pp. 1421-1431.
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