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Bleomycin N-Acetyltransferase and similar proteins BlmB, encodes a bleomycin N-acetyltransferase, designated BAT, which inactivates Bm using acetyl-coenzyme A (AcCoA). BAT forms a dimer structure via interaction of its C-terminal domains in the monomers. The N-terminal domain of BAT has a tunnel with two entrances: a wide entrance that accommodates the metal-binding domain of Bm and a narrow entrance that accommodates acetyl-CoA (AcCoA). A groove formed on the dimer interface of two BAT C-terminal domains forms the DNA-binding domain of Bm. In a ternary complex of BAT, BmA(2), and CoA, a thiol group of CoA is positioned near the primary amine of Bm at the midpoint of the tunnel and ensures efficient transfer of an acetyl group from AcCoA to the primary amine of Bm. BAT belongs to vicinal oxygen chelate (VOC) superfamily that is composed of structurally related proteins with paired beta.alpha.beta.beta.beta motifs that provide a metal coordination environment with two or three open or readily accessible coordination sites to promote direct electrophilic participation of the metal ion in catalysis. VOC domain is found in a variety of structurally related metalloproteins, including thiocoraline, bleomycin resistance protein, glyoxalase I, and type I ring-cleaving dioxygenases. A bound metal ion is required for protein activities for the members of this superfamily. A variety of metal ions have been found in the catalytic centers of these proteins including Fe(II), Mn(II), Zn(II), Ni(II) and Mg(II). The protein superfamily contains members with or without domain swapping. The proteins of this family share three conserved metal binding amino acids with the type I extradiol dioxygenases, which shows no domain swapping. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",