Hurme R, Namork E, Nurmiaho-Lassila E L, Rhen M
Department of Biochemistry, University of Helsinki, Finland.
J Biol Chem. 1994 Apr 8;269(14):10675-82.
The TlpA protein encoded by the virulence plasmid of Salmonella enterica is an alpha-helical 371-amino acid protein possessing characteristics similar to eukaryotic coiled coil proteins (Koski, P., Saarilahti, H., Sukupolvi, S., Taira, S., Rikkonen, P., Osterlund, K., Hurme, R., and Rhen, M. (1992) J. Biol. Chem. 267, 12258-12265). In this paper we have investigated inter- and intramolecular associations and the morphology of structures formed by TlpA. Dynamics and temperature stability of TlpA dimers were studied by examining the feasibility and conditions in which TlpA would form an artificial heterodimer with its truncated derivative. Formation of heterodimers, bridged by Cu(2+)-catalyzed air oxidation of adjacent Cys residues, showed that TlpA dimers are dynamic chain exchanging structures at 37 degrees C, whereas they were nonexchanging at room temperature or on ice. Chemical cross-linking suggested higher order interaction between TlpA dimers. Electron microscopy studies revealed two levels of TlpA organization in vitro: thin filaments and rods, 2-5 nm in diameter, and a higher ordered filament network consisting of tonofilament-like formations with a diameter of 8-15 nm. Electron microscopy of thin-sectioned Escherichia coli over-producing TlpA showed an extraordinary intracellular assembly of proteinacious lamellae with a striated appearance and a 38-nm periodicity. This study describes for the first time a bacterial protein capable of organizing itself into an ordered and suspectedly dynamic intermediate filament-like architecture.
肠炎沙门氏菌毒力质粒编码的TlpA蛋白是一种由371个氨基酸组成的α-螺旋蛋白，具有与真核卷曲螺旋蛋白相似的特征（科斯奇，P.，萨里拉赫蒂，H.，苏库波尔维，S.，泰拉，S.，里科宁，P.，奥斯特伦德，K.，胡尔梅，R.，和伦，M.（1992年）《生物化学杂志》267卷，12258 - 12265页）。在本文中，我们研究了TlpA的分子间和分子内缔合以及其形成结构的形态。通过研究TlpA与其截短衍生物形成人工异二聚体的可行性和条件，对TlpA二聚体的动力学和温度稳定性进行了研究。由相邻半胱氨酸残基的铜（2 +）催化空气氧化桥接形成的异二聚体表明，TlpA二聚体在37℃时是动态链交换结构，而在室温或冰上时是非交换结构。化学交联表明TlpA二聚体之间存在更高阶的相互作用。电子显微镜研究揭示了TlpA在体外的两种组织水平：直径为2 - 5nm的细丝和棒状物，以及由直径为8 - 15nm的张力丝样结构组成的更高阶细丝网络。对过量表达TlpA的大肠杆菌超薄切片进行电子显微镜观察，发现了一种具有条纹外观和38nm周期性的蛋白质薄片的特殊细胞内组装。这项研究首次描述了一种能够将自身组织成有序且疑似动态的中间丝样结构的细菌蛋白。
