Physical properties of Escherichia coli P pili measured by optical tweezers
Physical properties of Escherichia coli P pili measured by optical tweezers
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DOI：
10.1529/biophysj.104.044867
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发表时间：
2004-12-01
影响因子：
3.4
通讯作者：
Axner, O
中科院分区：
文献类型：
--
作者：
Jass, J;Schedin, S;Axner, O
利用光镊技术研究了致尿路感染大肠杆菌P皮利的力学行为。P皮利主要由10（3）个PapA亚基组成，呈螺旋状排列，分布于细菌表面，介导对宿主细胞的粘附。它们在大肠杆菌的发病机制中特别重要。大肠杆菌在上尿路和肾脏中定植。建立了一个生物模型系统，用于原位测量皮利机械拉伸过程中发生的力。建立了单个菌毛的力-伸长行为的数学模型。鉴定了皮利的三个延伸区。在区域I中，P皮利弹性伸展，最高达16 +/-3%的相对伸长。P菌毛的弹性模量和面积的乘积EA被评估为154 +/- 20 pN（n = 6）。在区域II中，PapA杆的四级结构在27 +/- 2 pN（n近似于100）的恒定力下通过连续破坏PapA亚基的相邻层之间的相互作用而展开。这种展开可以使菌毛延长7 +/-2倍。在区域III中，由于拉伸，皮利以非线性方式伸长，直到结合断裂。
The mechanical behavior of individual P pili of uropathogenic Escherichia coli has been investigated using optical tweezers. P pili, whose main part constitutes the PapA rod, composed of similar to10(3) PapA subunits in a helical arrangement, are distributed over the bacterial surface and mediate adhesion to host cells. They are particularly important in the pathogenesis of E. coli colonizing the upper urinary tract and kidneys. A biological model system has been established for in situ measurements of the forces that occur during mechanical stretching of pili. A mathematical model of the force-versus-elongation behavior of an individual pilus has been developed. Three elongation regions of pili were identified. In region I, P pili stretch elastically, up to a relative elongation of 16 +/- 3%. The product of elasticity modulus and area of a P pilus, EA, was assessed to 154 +/- 20 pN (n = 6). In region II, the quaternary structure of the PapA rod unfolds under a constant force of 27 +/- 2 pN ( n approximate to 100) by a sequential breaking of the interactions between adjacent layers of PapA subunits. This unfolding can elongate the pilus up to 7 +/- 2 times. In region III, pili elongate in a nonlinear manner as a result of stretching until the bond ruptures.