Bacteriophages penetrate the host cell membrane using their tail to inject genetic material into the host [1]. In this penetration process, they use central spike domain located beneath their baseplate [2]. The spike domain folds as a trimeric iron-binding structure [1]. This entry contains three copies of the repeat unit.

1: The host-binding domain of the P2 phage tail spike reveals a trimeric iron-binding structure. Yamashita E, Nakagawa A, Takahashi J, Tsunoda K, Yamada S, Takeda S; Acta Crystallogr Sect F Struct Biol Cryst Commun. 2011;67:837-841. PMID:21821878

2: Crystal structure of the C-terminal domain of Mu phage central spike and functions of bound calcium ion. Harada K, Yamashita E, Nakagawa A, Miyafusa T, Tsumoto K, Ueno T, Toyama Y, Takeda S; Biochim Biophys Acta. 2013;1834:284-291. PMID:22922659