β-Helix core packing within the triple-stranded oligomerization domain of the P22 tailspike

Authors

  • Jason F. Kreisberg,

    1. Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
    Current affiliation:
    1. Department of Physiology, Box 0444, University of California, 513 Parnassus Avenue, San Francisco, California 94143
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  • Scott D. Betts,

    1. Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
    Current affiliation:
    1. Novartis Agribusiness Biotechnology Research, Inc., 3054 Cornwallis Road, Research Triangle Park, North Carolina 27709
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  • Jonathan King

    Corresponding author
    1. Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
    • Department of Biology 68–330, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139
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Abstract

A right-handed parallel β-helix of 400 residues in 13 tightly packed coils is a major motif of the chains forming the trimeric P22 tailspike adhesin. The β-helix domains of three identical subunits are side-by-side in the trimer and make predominantly hydrophilic inter-subunit contacts (Steinbacher S et al., 1994, Science 265:383-386). After the 13th coil the three individual β-helices terminate and the chains wrap around each other to form three interdigitated β-sheets organized into the walls of a triangular prism. The β-strands then separate and form antiparallel β-sheets, but still defining a triangular prism in which each side is a β-sheet from a different subunit (Seckler R, 1998, J Struct Biol 122:216–222). The subunit interfaces are buried in the triangular core of the prism, which is densely packed with hydrophobic side chains from the three β-sheets. Examination of this structure reveals that its packed core maintains the same pattern of interior packing found in the left-handed β-helix, a single-chain structure. This packing is maintained in both the interdigitated parallel region of the prism and the following antiparallel sheet section. This oligomerization motif for the tailspike β-helices presumably contributes to the very high thermal and detergent stability that is a property of the native tailspike adhesin.

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