Dugdale T M, Dagastine R, Chiovitti A, Mulvaney P, Wetherbee R
School of Botany, School of Chemical and Biomolecular Engineering, University of Melbourne, Melbourne, Australia.
Biophys J. 2005 Dec;89(6):4252-60. doi: 10.1529/biophysj.105.062489. Epub 2005 Sep 16.
The adhesive and mechanical properties of a cell-substratum adhesive secreted by live diatom cells were examined in situ using atomic force microscopy. The resulting force curves have a regular saw-tooth pattern, the characteristic fingerprint of modular proteins, and when bridged between tip and surface can repeatedly be stretched and relaxed resulting in precisely overlaying saw-tooth curves (up to approximately 600 successive cycles). The average rupture force of the peaks is 0.794 +/- 0.007 (mean +/- SE) nN at a loading rate of 0.8 microm/s and the average persistence length is 0.026 +/- <0.001 (mean +/- SE) nm (fit using the worm-like chain model). We propose that we are pulling on single adhesive nanofibers, each a cohesive unit composed of a set number of modular proteins aligned in register. Furthermore, we can observe and differentiate when up to three adhesive nanofibers are pulled based upon multimodal distributions of force and persistence length. The high force required for bond rupture, high extensibility (approximately 1.2 microm), and the accurate and rapid refolding upon relaxation, together provide strong and flexible properties ideally suited for the cell-substratum adhesion of this fouling diatom and allow us to understand the mechanism responsible for the strength of adhesion.
利用原子力显微镜原位检测了活硅藻细胞分泌的细胞-基质黏附物的黏附及力学性能。所得力曲线呈现出规则的锯齿状图案，这是模块化蛋白质的特征指纹，当在探针与表面之间架桥时，其可反复拉伸和松弛，从而产生精确重叠的锯齿状曲线（多达约600个连续循环）。在加载速率为0.8微米/秒时，峰值的平均断裂力为0.794±0.007（平均值±标准误差）纳牛，平均持续长度为0.026±<0.001（平均值±标准误差）纳米（使用蠕虫状链模型拟合）。我们提出，我们正在拉动单个黏附性纳米纤维，每个纳米纤维都是由一定数量对齐排列的模块化蛋白质组成的内聚单元。此外，基于力和持续长度的多峰分布，当拉动多达三根黏附性纳米纤维时，我们能够进行观察和区分。键断裂所需的高力、高延伸性（约1.2微米）以及松弛时准确快速的重新折叠，共同提供了强大且灵活的性能，非常适合这种污损硅藻的细胞-基质黏附，并使我们能够理解负责黏附强度的机制。
