The bacteriophage Φ29 packaging proteins supercoil the DNA ends

Shelley Grimes, Dwight Anderson

Research output: Contribution to journalArticlepeer-review

64 Scopus citations


Bacteriophage Φ29 DNA with covalently bound terminal protein (DNA-gp3) and its left and right-end restriction fragments (L and R-DNA-gp3) sedimented faster in sucrose density gradients than their proteinase K-treated counterparts, and the faster sedimentation was both gp3 and Mg2+-dependent. Addition of gp16, the Φ29 DNA packaging ATPase, further increased the sedimentation rates of both intact DNA-gp3 and L and R-DNA-gp3 fragments. Thus, DNAs with gp3 were more compact than gp3-free DNA, and gp16 further condensed the DNA-gp3 forms. [35S]gp16 cosedimented with the fast-sedimenting DNA-gp3 fragments, and the putative L-DNA-gp3-gp16 complexes were packaged preferentially into proheads in the defined in vitro system. Lariats of DNA-gp3 and L and R-DNA-gp3 observed by electron microscopy rationalized the sedimentation results, and lariats with multiple loops or coils increased tenfold in a preparation of L-DNA-gp3-gp16 complexes. The rapid sedimentation and the structure of the DNA-gp3-gp16 complexes were consistent with supercoiling of lariat loops, and treatment with topoisomerase I shifted fast-sedimenting complexes toward the uncoiled lariat position in sucrose density gradients. DNA-gp3 has a maturation pathway in which the packaging proteins gp3 and gp16 supercoil the DNA ends, probably as a prerequisite for efficient interaction with the prohead.

Original languageEnglish (US)
Pages (from-to)901-914
Number of pages14
JournalJournal of Molecular Biology
Issue number5
StatePublished - Mar 14 1997

Bibliographical note

Funding Information:
We thank Sarah Turnquist for her excellent technical help and Charlene Peterson for preparation of the manuscript and for her expertise in generating Figures 7 and 8 . This work was supported by NIH research grants to D.A.


  • Bacteriophage Φ29
  • DNA maturation
  • DNA packaging proteins
  • DNA supercoiling
  • DNA topology


Dive into the research topics of 'The bacteriophage Φ29 packaging proteins supercoil the DNA ends'. Together they form a unique fingerprint.

Cite this