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Genetic and functional analyses of the øX174 DNA binding protein: the effects of substitutions for amino acid residues that spatially organize the two DNA binding domains

Authors
Journal
Virology
0042-6822
Publisher
Elsevier
Publication Date
Volume
318
Issue
1
Identifiers
DOI: 10.1016/j.virol.2003.09.018
Keywords
  • øX174
  • Microviridae
  • Dna Binding Protein
  • Ssdna
Disciplines
  • Biology

Abstract

Abstract The øX174 DNA binding protein contains two DNA binding domains, containing a series of DNA binding basic amino acids, separated by a proline-rich linker region. Within each DNA binding domain, there is a conserved glycine residue. Glycine and proline residues were mutated and the effects on virion structure were examined. Substitutions for glycine residues yield particles with similar properties to previously characterized mutants with substitutions for DNA binding residues. Both sets of mutations share a common extragenic second-site suppressor, suggesting that the defects caused by the mutant proteins are mechanistically similar. Hence, glycine residues may optimize DNA-protein contacts. The defects conferred by substitutions for proline residues appear to be fundamentally different. The properties of the mutant particles along with the atomic structure of the virion suggest that the proline residues may act to guide the packaged DNA to the adjacent fivefold related asymmetric unit, thus preventing a chaotic packaging arrangement.

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