具有钙钳的细菌粘附素延伸结构域具有异常高的机械稳定性。
Unusually high mechanical stability of bacterial adhesin extender domains having calcium clamps.
作者信息
Oude Vrielink Anneloes S, Vance Tyler D R, de Jong Arthur M, Davies Peter L, Voets Ilja K
机构信息
Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, Netherlands.
Laboratory of Macromolecular and Organic Chemistry, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, Netherlands.
出版信息
PLoS One. 2017 Apr 4;12(4):e0174682. doi: 10.1371/journal.pone.0174682. eCollection 2017.
To gain insight into the relationship between protein structure and mechanical stability, single molecule force spectroscopy experiments on proteins with diverse structure and topology are needed. Here, we measured the mechanical stability of extender domains of two bacterial adhesins MpAFP and MhLap, in an atomic force microscope. We find that both proteins are remarkably stable to pulling forces between their N- and C- terminal ends. At a pulling speed of 1 μm/s, the MpAFP extender domain fails at an unfolding force Fu = 348 ± 37 pN and MhLap at Fu = 306 ± 51 pN in buffer with 10 mM Ca2+. These forces place both extender domains well above the mechanical stability of many other β-sandwich domains in mechanostable proteins. We propose that the increased stability of MpAFP and MhLap is due to a combination of both hydrogen bonding between parallel terminal strands and intra-molecular coordination of calcium ions.
为深入了解蛋白质结构与机械稳定性之间的关系，需要对具有不同结构和拓扑结构的蛋白质进行单分子力谱实验。在此，我们在原子力显微镜中测量了两种细菌粘附素MpAFP和MhLap延伸结构域的机械稳定性。我们发现，这两种蛋白质在其N端和C端之间的拉力作用下都非常稳定。在1μm/s的拉伸速度下，在含有10mM Ca2+的缓冲液中，MpAFP延伸结构域在展开力Fu = 348±37 pN时失效，MhLap在Fu = 306±51 pN时失效。这些力使这两个延伸结构域的机械稳定性远高于机械稳定蛋白中许多其他β-三明治结构域。我们认为，MpAFP和MhLap稳定性的提高是由于平行末端链之间的氢键作用和钙离子的分子内配位共同作用的结果。
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