The first Cupredoxin domain of the multicopper oxidase CueO, the cell division protein FtsP, and similar proteins
CueO is a multicopper oxidase (MCO) that is part of the copper-regulatory cue operon, which employs a cytosolic metalloregulatory protein CueR that induces expression of CopA and CueO under copper stress conditions. CueO is a periplasmic multicopper oxidase that is stimulated by exogenous copper(II). FtsP (also named SufI) is a component of the cell division apparatus. It is involved in protecting or stabilizing the assembly of divisomes under stress conditions. FtsP belongs to the multicopper oxidase superfamily but lacks metal cofactors. The protein is localized at septal rings and may serve as a scaffolding function. Members of this subfamily contain three cupredoxin domains and this model represents the first domain. Although MCOs have diverse functions, majority of them have three cupredoxin domain repeats that include one mononuclear and one trinuclear copper center. The copper ions are bound in several sites: Type 1, Type 2, and/or Type 3. The ensemble of types 2 and 3 copper is called a trinuclear cluster. MCOs oxidize their substrate by accepting electrons at a mononuclear copper center and transferring them to the active site trinuclear copper center. The cupredoxin domain 1 of 3-domain MCOs contains part the trinuclear copper binding site, which is located at the interface of domains 1 and 3. FtsP does not contain any copper binding sites.
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