T4 short tail fiber

Fig. 7. Triple-stranded (TS) /8-solenoids. (A) Ribbon diagram of a fragment of the T4 short tail-fiber gpl2 (van Raaij et al., 2001) and (B) cross-sectional shapes of the TS //-solenoids. Repetitive turn-strand elements of each individual chain of the TS //-solenoids are rendered in different colors.

Fig. 6. Structure of the T4 short tail fiber. The structure of residues 246-527 is shown it is a composite of two partial structures (Thomassen et al., 2003 van Raaij et al., 2001a). The different domains are indicated the T4-fiber fold consisting of residues 246-286, the triple / -helix (residues 290-329), the collar domain (residues 330-396 and 518-527), and the receptor-binding domain (amino acids 397-517). The zinc ion in the center of the receptor-binding domain is shown as a gray sphere.

Because only one repeat is present in the structure and the number of amino acids between repeats is variable, we cannot yet draw conclusions about whether the monomers spiral around each other or whether this will be a left-handed or right-handed spiral. Future studies (Section IV) will hopefully lead to structural information on the repeat-containing N-terminal half of the bacteriophage T4 short tail fiber and the long tail fibers. 

The T4 short tail fiber triple /l-helix is connected to a more globular head domain via residues 333-341, which form a very short a-helical triple coiled-coil. Residues 342-396, together with the C-terminal /1-strand composed of amino acids 518-527 (the collar ), are the only part of the structure in which the monomer has a recognizable fold. It may therefore be the first part of the protein to fold, followed by a zipping-up of the N-terminal domain and the top domain. The small, globular, domain contains six /1-strands and one a-helix and has some structural homology to gpl 1, also of bacteriophage T4. Three of the /1-strands and the a-helix formed by residues... 

Burda, M. R., and Miller, S. (1999). Folding of coliphage T4 short tail fiber in vitro. Analysing the role of a bacteriophage-encoded chaperone. Eur. J. Biochem. 265, 771-778. 

Fig. 1. Schematic drawings of the viruses discussed in this chapter. (A) An icosahe-dral virus with fiber proteins inserted in its pentameric vertices. The gray box denotes domains with known structures for adenovirus, reovirus, and bacteriophage PRD1, in each case containing the head domain and proximal part of the triple /8-spiral shaft domain. (B) Contractile-tailed bacteriophage T4. T4 contains three different fibrous proteins, fibritin connected to the neck, the long (bent) fibers connected to the base plate, and the short fibers also connected to the base plate. Only two of each of the trimeric fibrous proteins are shown for clarity. The gray box denotes domains with known structure for the T4 short fiber.

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