LegC3 is an effector protein secreted by Legionella pneumophila which is believed to act by inhibiting vacuolar fusion. The N-terminal domain of LegC3 is composed of a long discontinuous coiled-coil capped by an antiparallel four-helix bundle that is rigidly connected to the coiled-coil segment. The features responsible for fusion inhibition are located mainly within the N-terminal domain, as this domain alone was sufficient to inhibit vacuole fusion, and that this domain remains associated with vacuoles [1].

1: Structure of the N-terminal domain of the effector protein LegC3 from Legionella pneumophila. Yao D, Cherney M, Cygler M; Acta Crystallogr D Biol Crystallogr. 2014;70:436-441. PMID:24531477