Ménard R, Sansonetti P, Parsot C, Vasselon T
Unité de Pathogénie Microbienne Moléculaire, Paris, France.
Cell. 1994 Nov 4;79(3):515-25. doi: 10.1016/0092-8674(94)90260-7.
Shigella species cause bacillary dysentery in humans by invading colonic epithelial cells. IpaB and IpaC, two major invasins of these pathogens, are secreted into the extracellular milieu. We show here that IpaB and IpaC form a complex in the extracellular medium and that each binds independently to a 17 kDa polypeptide, IpgC, in the bacterial cytoplasm. The IpgC polypeptide was found to be necessary for bacterial entry into epithelial cells, to stabilize the otherwise unstable IpaB protein, and to prevent the proteolytic degradation of IpaC that occurs through its association with unprotected IpaB. We propose that IpgC, which is not secreted and thus acts as a molecular chaperone, serves as a receptor that prevents premature oligomerization of IpaB and IpaC within the cytoplasm of Shigella cells.
志贺氏菌属通过侵入结肠上皮细胞导致人类患细菌性痢疾。这些病原体的两种主要侵袭素IpaB和IpaC被分泌到细胞外环境中。我们在此表明，IpaB和IpaC在细胞外培养基中形成复合物，并且它们各自独立地与细菌细胞质中的一种17 kDa多肽IpgC结合。发现IpgC多肽对于细菌进入上皮细胞是必需的，可稳定原本不稳定的IpaB蛋白，并防止因IpaC与未受保护的IpaB结合而发生的蛋白水解降解。我们提出，不被分泌因而充当分子伴侣的IpgC作为一种受体，可防止志贺氏菌细胞胞质内IpaB和IpaC过早寡聚化。
