Jones C H, Danese P N, Pinkner J S, Silhavy T J, Hultgren S J
Department of Molecular Microbiology, Washington University Medical School, St Louis, MO 63110, USA.
EMBO J. 1997 Nov 3;16(21):6394-406. doi: 10.1093/emboj/16.21.6394.
The assembly of interactive protein subunits into extracellular structures, such as pilus fibers in the Enterobacteriaceae, is dependent on the activity of PapD-like periplasmic chaperones. The ability of PapD to undergo a beta zippering interaction with the hydrophobic C-terminus of pilus subunits facilitates their folding and release from the cytoplasmic membrane into the periplasm. In the absence of the chaperone, subunits remained tethered to the membrane and were driven off-pathway via non-productive interactions. These off-pathway reactions were detrimental to cell growth; wild-type growth was restored by co-expression of PapD. Subunit misfolding in the absence of PapD was sensed by two parallel pathways: the Cpx two-component signaling system and the sigma E modulatory pathway.
交互式蛋白质亚基组装成细胞外结构，如肠杆菌科的菌毛纤维，依赖于类PapD周质伴侣蛋白的活性。PapD与菌毛亚基疏水C末端进行β拉链相互作用的能力，有助于它们折叠并从细胞质膜释放到周质中。在没有伴侣蛋白的情况下，亚基仍与膜相连，并通过非生产性相互作用偏离正常途径。这些偏离正常途径的反应对细胞生长有害；通过共表达PapD可恢复野生型生长。在没有PapD的情况下，亚基错误折叠通过两条平行途径被感知：Cpx双组分信号系统和σE调节途径。
