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Interaction of gp16 with pRNA and DNA for genome packaging by the motor of bacterial virus phi29

Tae-Jin Lee1, Peixuan Guo

  • 1Department of Pathobiology, Weldon School of Biomedical Engineering, and Cancer Center, Purdue University, West Lafayette, IN 47907, USA.

Journal of Molecular Biology
|December 27, 2005
PubMed

Insights

Researchers elucidated the role of protein gp16 in viral DNA packaging. Soluble gp16 binds strongly to procapsids containing packaging RNA (pRNA), suggesting it links pRNA and DNA during translocation.

Area of Science:

  • Molecular Biology
  • Virology
  • Structural Biology

Background:

  • Viral DNA packaging into protein coats utilizes motors with ATPase characteristics.
  • Bacteriophage phi29 employs protein gp16 and packaging RNA (pRNA) in its DNA packaging motor.
  • Previous studies on gp16 were hindered by its hydrophobicity and aggregation, leading to conflicting data on its function.

Purpose of the Study:

  • To investigate the role of protein gp16 in the phi29 DNA packaging motor.
  • To overcome previous limitations by producing soluble and active gp16.
  • To determine the binding interactions of gp16 with other motor components, specifically pRNA and procapsids.

Main Methods:

  • Production of soluble and highly active protein gp16.
  • Binding assays to assess interactions between gp16, DNA, pRNA, and procapsids.
  • Analysis of specific pRNA domains involved in gp16 interaction.

Main Results:

  • Soluble gp16 demonstrated non-specific binding to DNA.
  • gp16 exhibited significantly stronger binding to pRNA-containing procapsids compared to pRNA-free procapsids.
  • The 5'/3' paired helical region of pRNA was identified as the interaction site for gp16, while the C18C19A20 bulge was dispensable for gp16 binding.

Conclusions:

  • gp16 acts as a crucial linker between pRNA and DNA, and as a DNA-contacting component during viral DNA translocation.
  • The 5'/3' helical region of pRNA primarily functions in binding gp16, rather than binding to the procapsid, except for the C18C19A20 bulge.
  • These findings clarify the role of gp16 and pRNA in the phi29 DNA packaging motor mechanism.

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