Marlovits Thomas C, Kubori Tomoko, Sukhan Anand, Thomas Dennis R, Galán Jorge E, Unger Vinzenz M
Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520-8024, USA.
Science. 2004 Nov 5;306(5698):1040-2. doi: 10.1126/science.1102610.
Type III secretion systems (TTSSs) mediate translocation of virulence factors into host cells. We report the 17-angstrom resolution structures of a central component of Salmonella typhimurium TTSS, the needle complex, and its assembly precursor, the bacterial envelope-anchored base. Both the base and the fully assembled needle complex adopted multiple oligomeric states in vivo, and needle assembly was accompanied by recruitment of the protein PrgJ as a structural component of the base. Moreover, conformational changes during needle assembly created scaffolds for anchoring both PrgJ and the needle substructure and may provide the basis for substrate-specificity switching during type III secretion.
III型分泌系统（TTSSs）介导毒力因子转运至宿主细胞内。我们报道了鼠伤寒沙门氏菌TTSS的一个核心组分——针状复合物及其组装前体（细菌包膜锚定基座）的17埃分辨率结构。基座和完全组装好的针状复合物在体内均呈现多种寡聚状态，并且针状结构的组装伴随着蛋白质PrgJ作为基座结构组分的募集。此外，针状结构组装过程中的构象变化为锚定PrgJ和针状亚结构创造了支架，可能为III型分泌过程中底物特异性转换提供了基础。
