Self-association properties of the bacteriophage lambda terminase holoenzyme: implications for the DNA packaging motor

J Mol Biol. 2005 Apr 1;347(3):523-42. doi: 10.1016/j.jmb.2005.01.016. Epub 2005 Jan 20.


Terminases are enzymes common to complex double-stranded DNA viruses and are required for packaging of viral DNA into a protective capsid. Bacteriophage lambda terminase holoenzyme is a hetero-oligomer composed of the A and Nu1 lambda gene products; however, the self-association properties of the holoenzyme have not been investigated systematically. Here, we report the results of sedimentation velocity, sedimentation equilibrium, and gel-filtration experiments studying the self-association properties of the holoenzyme. We find that purified, recombinant lambda terminase forms a homogeneous, heterotrimeric structure, consisting of one gpA molecule associated with two gpNu1 molecules (114.2 kDa). We further show that lambda terminase adopts a heterogeneous mixture of higher-order structures, with an average molecular mass of 528(+/-34) kDa. Both the heterotrimer and the higher-order species possess site-specific cos cleavage activity, as well as DNA packaging activity; however, the heterotrimer is dependent upon Escherichia coli integration host factor (IHF) for these activities. Furthermore, the ATPase activity of the higher-order species is approximately 1000-fold greater than that of the heterotrimer. These data suggest that IHF bending of the duplex at the cos site in viral DNA promotes the assembly of the heterotrimer into a biologically active, higher-order packaging motor. We propose that a single, higher-order hetero-oligomer of gpA and gpNu1 functions throughout lambda development.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphatases / metabolism
  • Bacteriophage lambda / enzymology*
  • Bacteriophage lambda / genetics
  • DNA Packaging*
  • DNA, Viral / metabolism
  • Endodeoxyribonucleases / chemistry*
  • Endodeoxyribonucleases / metabolism
  • Holoenzymes / chemistry*
  • Holoenzymes / metabolism
  • Hydrogen-Ion Concentration
  • Models, Genetic
  • Molecular Motor Proteins / chemistry*
  • Molecular Motor Proteins / metabolism
  • Molecular Weight
  • Protein Isoforms / chemistry
  • Protein Isoforms / metabolism
  • Protein Structure, Quaternary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Temperature
  • Viral Proteins / chemistry
  • Viral Proteins / metabolism


  • DNA, Viral
  • Holoenzymes
  • Molecular Motor Proteins
  • Protein Isoforms
  • Recombinant Proteins
  • Viral Proteins
  • Endodeoxyribonucleases
  • terminase
  • Adenosine Triphosphatases