Structures of Viral Fibers

Crystal Structures of Viral Fibers A. Morphology of Viral Fibers 

Adenovirus, Reovirus, and Phage PRD1 Fiber Head Domains 

The partial structure of the adenovirus type 2 fiber shaft was the first /(-structured fibrous fold characterized at atomic detail. The shaft contains 15-residue sequence pseudo-repeats with an invariant glycine or proline and conserved hydrophobic amino acids (Fig. 3A Green et al., 1983). Unfolding studies led to the identification of a stable domain, consisting of amino acids 319-582, which was subcloned, expressed, and purified (Mitraki et al., 1999). Subsequently, it was crystallized, and its structure solved at 2.4-A resolution (van Raaij et al., 1999b). Its structure revealed a new fold, called the triple /(-spiral.  

More recently, triple /1-spiral repeats have been identified in mammalian reovirus type 3 fiber (Chappell et al., 2002 Fig. 4A), avian reovirus fiber (Guardado Calvo et al., 2005 Fig. 4B), and bacteriophage PRD1 P5 protein (Merckel et al., 2005 Fig. 4C). In the latter two cases, it appears that only two repeats are present, just N-terminal to the head domain. Mammalian reovirus fiber contains eight putative triple /1-spiral repeats, of which three were resolved in the crystal structure (Chappell et al., 2002). 

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