Keizer D W, Slupsky C M, Kalisiak M, Campbell A P, Crump M P, Sastry P A, Hazes B, Irvin R T, Sykes B D
Protein Engineering Network Centres of Excellence (PENCE), 713 Heritage Medical Research Centre, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
J Biol Chem. 2001 Jun 29;276(26):24186-93. doi: 10.1074/jbc.M100659200. Epub 2001 Apr 9.
Type IV pilin monomers assemble to form fibers called pili that are required for a variety of bacterial functions. Pilin monomers oligomerize due to the interaction of part of their hydrophobic N-terminal alpha-helix. Engineering of a truncated pilin from Pseudomonas aeruginosa strain K122-4, where the first 28 residues are removed from the N terminus, yields a soluble, monomeric protein. This truncated pilin is shown to bind to its receptor and to decrease morbidity and mortality in mice upon administration 15 min before challenge with a heterologous strain of Pseudomonas. The structure of this truncated pilin reveals an alpha-helix at the N terminus that lies across a 4-stranded antiparallel beta-sheet. A model for a pilus is proposed that takes into account both electrostatic and hydrophobic interactions of pilin subunits as well as previously published x-ray fiber diffraction data. Our model indicates that DNA or RNA cannot pass through the center of the pilus, however, the possibility exists for small organic molecules to pass through indicating a potential mechanism for signal transduction.
IV型菌毛单体组装形成称为菌毛的纤维，这是多种细菌功能所必需的。菌毛单体由于其疏水性N端α-螺旋部分的相互作用而寡聚化。对铜绿假单胞菌K122 - 4菌株的截短菌毛蛋白进行工程改造，从N端去除前28个残基，得到一种可溶性单体蛋白。这种截短的菌毛蛋白被证明能与其受体结合，并在在用异源铜绿假单胞菌菌株攻击前15分钟给药时降低小鼠的发病率和死亡率。这种截短菌毛蛋白的结构揭示了N端的一个α-螺旋，它横跨一个4股反平行β-折叠。提出了一种菌毛模型，该模型考虑了菌毛蛋白亚基的静电和疏水相互作用以及先前发表的X射线纤维衍射数据。我们的模型表明，DNA或RNA不能穿过菌毛的中心，然而，小分子有机分子有可能穿过，这表明存在一种信号转导的潜在机制。
