Department of Biological Sciences, National University of Singapore, Singapore 117543, Singapore.
J Struct Biol. 2011 Jul;175(1):31-8. doi: 10.1016/j.jsb.2011.04.013. Epub 2011 Apr 24.
Dodecins (assembly of twelve monomers) are the smallest known flavoprotein with only 65-73 amino acids and are involved in binding and storage of flavins in archaea. Here we report the crystal structure of Rv1498A, a Mycobacterium tuberculosis dodecin. This bacterial dodecin structure is similar to that of other reported dodecins. Each monomer has a 3 stranded β-sheet and an α-helix perpendicular to it. This protein has polyextreme (halophilic and thermophilic) properties. Interestingly, positively and negatively charged residues aggregate separately and do not seem to contribute to thermophilic and halophilic stability. We have examined the interactions that stabilize the Rv1498A dodecamer by preparing selected point mutants that break salt bridges and hydrophobic contacts, thereby leading to collapse of the assembly.
十二聚体（由十二个单体组成）是已知的最小黄素蛋白，只有 65-73 个氨基酸，参与古菌中黄素的结合和储存。在这里，我们报告了结核分枝杆菌十二聚体 Rv1498A 的晶体结构。这种细菌的十二聚体结构与其他报道的十二聚体相似。每个单体都有一个 3 股 β-折叠和一个与其垂直的 α-螺旋。这种蛋白质具有多极值（嗜盐和嗜热）特性。有趣的是，带正电荷和带负电荷的残基分别聚集，似乎对嗜热和嗜盐稳定性没有贡献。我们通过制备破坏盐桥和疏水接触的选定点突变体来检查稳定 Rv1498A 十二聚体的相互作用，从而导致组装的崩溃。
