Cupredoxin superfamily; Cupredoxins contain type I copper centers and are involved in inter-molecular electron transfer reactions. Cupredoxins are blue copper proteins, having an intense blue color due to the presence of a mononuclear type 1 (T1) copper site. Structurally, the cupredoxin-like fold consists of a beta-sandwich with 7 strands in 2 beta-sheets, which is arranged in a Greek-key beta-barrel. Some of these proteins have lost the ability to bind copper. The majority of family members contain multiple cupredoxin domain repeats: ceruloplasmin and the coagulation factors V/VIII have six repeats; laccase, ascorbate oxidase, spore coat protein A, and multicopper oxidase CueO contain three repeats; and nitrite reductase has two repeats. Others are mono-domain cupredoxins, such as plastocyanin, pseudoazurin, plantacyanin, azurin, rusticyanin, stellacyanin, quinol oxidase, and the periplasmic domain of cytochrome c oxidase subunit II.

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gi 999799050   1 MELFGYMDRYIWFINGLPEYKAKPILIKR 29
Cdd:cd13896    6 LHLTGNMERYVWTINGKAYPDADPLRVRE 34

The third cupredoxin domain of CopA copper resistance protein family; CopA is a multicopper oxidase (MCO) related to laccase and L-ascorbate oxidase, both copper-containing enzymes. It 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. CopA is a copper efflux P-type ATPase that is located in the inner cell membrane and is is involved in copper resistance in bacteria. CopA mutant causes a loss of function including copper tolerance and oxidase activity and copA transcription is inducible in the presence of copper. 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 3 of 3-domain MCOs contains the Type 1 (T1) copper binding site and part the trinuclear copper binding site, which is located at the interface of domains 1 and 3.

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                 ....*....|....*....|....*....
gi 999799050   1 MELFGYMDRYIWFINGLPEYKAKPILIKR 29
Cdd:cd13896    6 LHLTGNMERYVWTINGKAYPDADPLRVRE 34

The third cupredoxin domain of CopA copper resistance protein family; CopA is a multicopper oxidase (MCO) related to laccase and L-ascorbate oxidase, both copper-containing enzymes. It 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. CopA is a copper efflux P-type ATPase that is located in the inner cell membrane and is is involved in copper resistance in bacteria. CopA mutant causes a loss of function including copper tolerance and oxidase activity and copA transcription is inducible in the presence of copper. 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 3 of 3-domain MCOs contains the Type 1 (T1) copper binding site and part the trinuclear copper binding site, which is located at the interface of domains 1 and 3.

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                 ....*....|....*....|....*....
gi 999799050   1 MELFGYMDRYIWFINGLPEYKAKPILIKR 29
Cdd:cd13896    6 LHLTGNMERYVWTINGKAYPDADPLRVRE 34