IcmR plays a role in the Dot/Icm translocase from Legionella pneumophila. This Type IVb secretion system (T4bSS) is responsible for the delivery of protein effectors to the host cell cytoplasm. The middle region of IcmR (this entry) binds to the N-terminal domain of IcmQ, which is essential for IcmQ (Pfam:PF09475) to function correctly. The interacting domains form helical hairpins within a four-helix bundle that is stabilized by hydrophobic packing [1,2].

1: Structure and function of interacting IcmR-IcmQ domains from a type IVb secretion system in Legionella pneumophila. Raychaudhury S, Farelli JD, Montminy TP, Matthews M, Menetret JF, Dumenil G, Roy CR, Head JF, Isberg RR, Akey CW; Structure. 2009;17:590-601. PMID:19368892

2: IcmQ in the Type 4b secretion system contains an NAD+ binding domain. Farelli JD, Gumbart JC, Akey IV, Hempstead A, Amyot W, Head JF, McKnight CJ, Isberg RR, Akey CW; Structure. 2013;21:1361-1373. PMID:23850453