Beta-helix core packing within the triple-stranded oligomerization domain of the P22 tailspike.
A right-handed parallel beta-helix of 400 residues in 13 tightly packed coils is a major motif of the chains forming the trimeric P22 tailspike adhesin. The beta-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 beta-helices terminate and the chains wrap around each other to form three interdigitated beta-sheets organized into the walls of a triangular prism. The beta-strands then separate and form antiparallel beta-sheets, but still defining a triangular prism in which each side is a beta-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 beta-sheets. Examination of this structure reveals that its packed core maintains the same pattern of interior packing found in the left-handed beta-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 beta-helices presumably contributes to the very high thermal and detergent stability that is a property of the native tailspike adhesin.
Kreisberg
J F
JF
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
Betts
S D
SD
King
J
J
D018829:Adhesins, Bacterial / Q000737:chemistry*; D000595:Amino Acid Sequence; D019281:Dimerization; D006026:Glycoside Hydrolases / Q000737:chemistry*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011489:Protein Denaturation; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits; D017376:Viral Tail Proteins / Q000737:chemistry*
D018829:Adhesins, Bacterial; D021122:Protein Subunits; D017376:Viral Tail Proteins; D006026:Glycoside Hydrolases; C083268:tailspike protein, bacteriophage