Gomes Cláudio M, Frazão Carlos, Xavier António V, Legall Jean, Teixeira Miguel
Instituto de Tecnologia Química e Biológica (ITQB), Universidade Nova de Lisboa, APT 127, 2780-156 Oeiras, Portugal.
Protein Sci. 2002 Mar;11(3):707-12. doi: 10.1110/ps.31202.
At present there are three protein families that share a common structural domain, the alphabeta/betaalpha fold of class B beta-lactamases: zinc beta-lactamases, glyoxalases II, and A-type flavoproteins. A detailed inspection of their superimposed structures was undertaken and showed that although these proteins contain binuclear metal sites in spatially equivalent positions, there are some subtle differences within the first ligand sphere that determine a distinct composition of metals. Although zinc beta-lactamases contain either a mono or a di-zinc center, the catalytically active form of glyoxalase II contains a mixed iron-zinc binuclear center, whereas A-type flavoproteins contain a di-iron site. These variations on the type of metal site found within a common fold are correlated with the subtle variations in the nature of the ligating amino acid residues and are discussed in terms of the different reactions catalyzed by each of the protein families. Correlation of these observations with sequence data results in the definition of a sequence motif that comprises the possible binuclear metal site ligands in this broad family. The evolution of the proteins sharing this common fold and factors modulating reactivity are also discussed.
目前有三个蛋白质家族共享一个共同的结构域，即B类β-内酰胺酶的αβ/βα折叠：锌β-内酰胺酶、乙二醛酶II和A型黄素蛋白。对它们的叠加结构进行了详细检查，结果表明，尽管这些蛋白质在空间等效位置含有双核金属位点，但在第一个配体球内存在一些细微差异，这些差异决定了金属的不同组成。尽管锌β-内酰胺酶含有单锌或双锌中心，但乙二醛酶II的催化活性形式含有混合的铁-锌双核中心，而A型黄素蛋白含有双铁位点。在共同折叠中发现的金属位点类型的这些变化与连接氨基酸残基性质的细微变化相关，并根据每个蛋白质家族催化的不同反应进行了讨论。将这些观察结果与序列数据相关联，定义了一个序列基序，该基序包含这个广泛家族中可能的双核金属位点配体。还讨论了共享这种共同折叠的蛋白质的进化以及调节反应性的因素。
