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Title: Structure of a bacterial virus DNA-injection protein complex reveals a decameric assembly with a constricted molecular channel

The multi-layered cell envelope structure of Gram-negative bacteria represents significant physical and chemical barriers for short-tailed phages to inject phage DNA into the host cytoplasm. Here we show that a DNA-injection protein of bacteriophage Sf6, gp12, forms a 465-kDa, decameric assembly in vitro. The electron microscopic structure of the gp12 assembly shows a ~150-Å, mushroom-like architecture consisting of a crown domain and a tube-like domain, which embraces a 25-Å-wide channel that could precisely accommodate dsDNA. The constricted channel suggests that gp12 mediates rapid, uni-directional injection of phage DNA into host cells by providing a molecular conduit for DNA translocation. The assembly exhibits a 10-fold symmetry, which may be a common feature among DNA-injection proteins of P22-like phages and may suggest a symmetry mismatch with respect to the 6-fold symmetric phage tail. As a result, the gp12 monomer is highly flexible in solution, supporting a mechanism for translocation of the protein through the conduit of the phage tail toward the host cell envelope, where it assembles into a DNA-injection device.
 [1] ;  [2] ;  [3] ;  [1] ;  [1] ;  [1] ;  [1] ;  [3] ;  [1] ;  [4]
  1. Univ. of Kansas, Lawrence, KS (United States)
  2. The Scripps Research Institute, La Jolla, CA (United States)
  3. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  4. ContraFect Corp., Yonkers, NY (United States)
Publication Date:
OSTI Identifier:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Additional Journal Information:
Journal Volume: 11; Journal Issue: 2; Journal ID: ISSN 1932-6203
Public Library of Science
Research Org:
SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
59 BASIC BIOLOGICAL SCIENCES bacteriophages; host cells; protein structure; negative staining; cell membranes; viral packaging; DNA structure; molecular structure