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Function of a viral genome packaging motor from bacteriophage T4 is insensitive to DNA sequence

Youbin Mo1, Nicholas Keller1, Damian delToro1

  • 1Department of Physics, University of California, San Diego, La Jolla, CA 92093, USA.

Nucleic Acids Research
|October 29, 2020
PubMed

Insights

Viral DNA packaging motors show no sequence-specific behavior. Studies reveal that motor velocity, pausing, and slipping during DNA translocation are mainly random, not influenced by specific DNA sequences.

Area of Science:

  • Virology
  • Molecular Biology
  • Biophysics

Background:

  • Viruses utilize ATP-powered motors for DNA translocation into procapsid shells during assembly.
  • The influence of DNA sequence on viral motor function remains an open question, with some studies suggesting potential sequence-specific interactions.

Purpose of the Study:

  • To investigate whether the DNA sequence affects the function of the phage T4 viral DNA packaging motor.
  • To determine if specific DNA sequences, such as A-philic or GC-rich sequences, alter motor translocation rates, pausing, or slipping.

Main Methods:

  • Single-molecule optical tweezers were used to measure the translocation of various DNA sequences (phage, plasmid, synthetic A-philic, GC-rich) by the T4 motor.
  • Correlation analyses were performed across multiple packaging events to assess sequence dependence.

Main Results:

  • No significant differences in motor velocity were observed across different DNA sequences, including A-philic sequences.
  • Motor pausing showed no significant changes, and slipping exhibited only modest alterations regardless of DNA sequence.
  • Correlation analyses did not reveal significant sequence-position-dependent effects on packaging rate, pausing, or slipping.

Conclusions:

  • Viral genome packaging by the T4 motor appears to be largely insensitive to the substrate DNA sequence.
  • Observed fluctuations in motor velocity, pausing, and slipping are primarily stochastic temporal events rather than sequence-driven phenomena.

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