Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
J Am Soc Mass Spectrom. 2013 Sep;24(9):1328-37. doi: 10.1007/s13361-013-0677-y.
Maturation of the nickel-containing urease of Klebsiella aerogenes is facilitated by the UreD, UreF, and UreG accessory proteins along with the UreE metallo-chaperone. A fusion of the maltose binding protein and UreD (MBP-UreD) was co-isolated with UreF and UreG in a soluble complex possessing a (MBPUreD: UreF:UreG)2 quaternary structure. Within this complex a UreF:UreF interaction was identified by chemical cross-linking of the amino termini of its two UreF protomers, as shown by mass spectrometry of tryptic peptides. A preactivation complex was formed by the interaction of (MBP-UreD:UreF:UreG)2 and urease. Mass spectrometry of intact protein species revealed a pathway for synthesis of the urease pre-activation complex in which individual hetero-trimer units of the (MBP-UreD:UreF:UreG)2 complex bind to urease. Together, these data provide important new insights into the structures of protein complexes associated with urease activation.
产碱杆菌属的含镍脲酶的成熟是由 UreD、UreF 和 UreG 辅助蛋白以及 UreE 金属伴侣蛋白辅助完成的。麦芽糖结合蛋白和 UreD（MBP-UreD）的融合物与 UreF 和 UreG 一起共分离，形成具有（MBPUreD：UreF：UreG）2 四级结构的可溶性复合物。在该复合物中，通过其两个 UreF 前体的氨基末端的化学交联鉴定出 UreF:UreF 相互作用，如胰蛋白酶肽的质谱分析所示。（MBP-UreD：UreF：UreG）2 和脲酶的相互作用形成了预激活复合物。完整蛋白质物种的质谱分析揭示了脲酶预激活复合物合成的途径，其中（MBP-UreD：UreF：UreG）2 复合物的各个异三聚体单元与脲酶结合。这些数据共同为与脲酶激活相关的蛋白质复合物的结构提供了重要的新见解。
