ADP-ribosylation of actin
ADP-ribosylation of actin
复制标题
肌动蛋白的 ADP-核糖基化
DOI：
10.1007/bf01766487
复制
发表时间：
1990
影响因子：
2.7
通讯作者：
K. Aktories
中科院分区：
文献类型：
--
作者：
K. Aktories
调节蛋白的ADP核糖基化是细菌毒素作用于真核细胞功能的重要病理生理机制。这个毒素家族的著名成员是白喉毒素、霍乱毒素和百日咳毒素。白喉毒素ADP-核糖基化延伸因子2从而抑制蛋白质合成，而霍乱和百日咳毒素修饰参与跨膜信号转导的G-蛋白（参见A1 thaus和Richter，1987的综述）。最近，研究表明，各种梭菌毒素通过肌动蛋白的腺苷三磷酸化作用干扰真核生物。在这些毒素中有肉毒杆菌C2毒素（Aktories等人，1986）、产气荚膜梭菌iota毒素（Schering等人，1988）、螺形梭菌毒素（Simpson等人，1989）和由艰难梭菌产生的ADP-核糖基转移酶（Popoff等人，1988年）。所有这些毒素在结构上都是二元的，由两个非连接的组分组成。酶活性组分具有ADP-核糖基转移酶活性，结合组分参与毒素转移到细胞中（Ohishi & Miyake，1985）。C.产气荚膜梭菌iota毒素、C. spiroforme毒素和C.二聚ADP-核糖基转移酶具有免疫相关性，其结合成分可以相互替代。相反，肉毒杆菌C2毒素既不与那些毒素交叉反应，也不能与它们互换（Simpson等人，1989年）。ADP核糖基化毒素的底物是单体G-肌动蛋白，而不是聚合的F-肌动蛋白。因此，降低肌动蛋白临界浓度并诱导聚合的鬼笔环肽抑制肌动蛋白的ADP-核糖基化（Schering等人，1988年）。到目前为止，所研究的所有腺苷三磷酸化毒素都在肉毒杆菌素-I77处修饰肌动蛋白，如在肉毒杆菌C2毒素的情况下通过直接蛋白质化学分析所示（Vandekerckhove等人，1988）和产气荚膜杆菌i毒素，以及在其它毒素的情况下间接（毒素预处理）。不同肌动蛋白亚型的ADP-核糖基化揭示了特定的底物特异性。而C.产气荚膜杆菌iota毒素修饰迄今为止研究的所有肌动蛋白亚型，包括骨骼肌、心肌、平滑肌和非肌肉肌动蛋白，肉毒杆菌C2毒素ADP-核糖基化非肌肉fl/y-肌动蛋白和平滑肌？肌动蛋白但显然没有其它肌动蛋白同种型（Schering等，1988年）。肌动蛋白的ADP-核糖基化对肌动蛋白的性质产生了严重的功能后果。ADP-核糖基化的肌动蛋白失去了它的粘附能力（Aktories等人，1986年）。此外，ADP-核糖基化肌动蛋白具有肌动蛋白加帽蛋白的性质，其结合肌动蛋白丝的倒刺末端，从而抑制肌动蛋白丝快速生长末端的成核聚合（Wegner & Aktories，1988）。相比之下，修饰后的肌动蛋白不会干扰先前在倒刺末端用凝溶胶蛋白覆盖的细丝尖端的肌动蛋白聚合。因此，ADPribosylated肌动蛋白增加的临界浓度的单体肌动蛋白的值典型的聚合在尖端的肌动蛋白丝。ADP核糖基化肌动蛋白与肌动蛋白丝倒刺末端结合的解离常数约为10 - 8。肌动蛋白的腺苷二磷酸化抑制肌动蛋白催化的ATP水解（Geipel等人，1989年）。在低于其临界浓度的G-肌动蛋白和细胞松弛素刺激的G-肌动蛋白ATP酶的情况下观察到这种抑制作用，表明ATP水解的抑制不仅仅是由于肌动蛋白聚合的阻断（Geipel等人，1990年）。毒素对肌动蛋白的ADP-核糖基化在高浓度的烟酰胺（30 mM）下是可逆的，并导致肌动蛋白性质的重建，例如肌动蛋白ATP酶活性的增加（Just等人，1989年）。用肉毒杆菌C2毒素处理完整细胞引起细胞的聚集，这种作用伴随着微丝网络的破坏和细胞G-肌动蛋白的量的增加（Reuner等人，1987年）。解释毒素作用的模型包括以下步骤：首先，肉毒杆菌C2毒素（C2 II，100 000 kDa）的结合组分被蛋白水解切割成88 kDa片段，该片段与靶细胞的细胞表面结合，从而暴露毒素组分I的附着位点。酶活性组分I通过未知的机制转移到细胞中，ADP-核糖基化细胞G-核糖基核糖
ADP-ribosylation of regulatory proteins is an important pathophysiological mechanism by which various bacterial toxins act on eukaryotic cell functions. Well-known members of this family of toxins are diphtheria-, cholera-, and pertussis toxins. Whereas diphtheria toxin ADP-ribosylares elongation factor 2 thereby inhibiting protein synthesis, cholera-, and pertussis toxin modify G-proteins involved in transmembrane signal transduction (see A1thaus & Richter, 1987 for a review). Recently, it has been shown that various clostridial toxins interfere with the eukaryotic organism by ADPribosylation of actin. Among these toxins are botulinum C2 toxin (Aktories et al., 1986), Clostridium perfringens iota toxin (Schering et al., 1988), Clostridium spiroforme toxin (Simpson et al., 1989) and an ADP-ribosyltransferase produced by Clostridium difficile (Popoff et al., 1988). All these toxins are binary in structure and consist of two non-linked components. The enzymatically active component possesses ADP-ribosyltransferase activity and the binding component is involved in the transfer of the toxin into the cell (Ohishi & Miyake, 1985). C. perfringens iota toxin, C. spiroforme toxin and C. di~cile ADP-ribosyltransferase are immunologically related and their binding components can substitute for each other. In contrast, botulinum C2 toxin neither cross-reacts with those toxins nor can it be inter-changed with them (Simpson et al., 1989). The substrate of ADP-ribosylating toxins is monomeric G-actin but not polymerized F-actin. Therefore, phalloidin which decreases the critical concentration of actin and induces polymerization, inhibits ADP-ribosylation of actin (Schering et aI., 1988). So far all the ADPribosylating toxins studied modify actin at arginine-I77, as shown by direct protein chemical analysis in the case of botulinum C2 toxin (Vandekerckhove et al., 1988) and perfringens iota toxin and indirectly (toxin pretreatment) in the case of the other toxins. ADP-ribosylation of different actin isoforms reveals a particular substrate specificity. Whereas, C. perfringens iota toxin modifies all actin isoforms studied so far, including skeletal muscle, cardiac muscle, smooth muscle and nonmuscle actin, botulinum C2 toxin ADP-ribosylates nonmuscle fl/y-actin and smooth muscle ?-actin but apparently no other actin isoforms (Schering et al., 1988). ADP-ribosylation of actin gives rise to drastic functional consequences for the properties of actin. ADP-ribosylated actin loses its ability to polymerize (Aktories et al., 1986). Furthermore, the ADP-ribosylated actin has the property of an actin capping protein, which binds to the barbed ends of actin filaments thereby inhibiting nucleated polymerization at the fast growing end of actin filaments (Wegner & Aktories, 1988). In contrast, the modified actin does not interfere with actin polymerization at the pointed ends of filaments previously capped with gelsolin at the barbed end. Accordingly, ADPribosylated actin increased the critical concentration of monomeric actin to values typical for the polymerization at the pointed end of actin filaments. The dissociation constant for the binding of ADP-ribosylated actin to the barbed end of actin filaments is about 10 -8. ADPribosylation of actin inhibits the ATP hydrolysis catalyzed by actin (Geipel et al., 1989). This inhibitory effect is observed with G-actin below its critical concentration and with cytochalasin-stimulated G-actin ATPase indicating that inhibition of ATP hydrolysis is not simply due to the blockade of actin polymerization (Geipel et al., 1990). ADP-ribosylation of actin by the toxins is reversible at high concentrations of nicotinamide (30 mM) and results in the reconstitution of actin properties, such as an increase in actin ATPase activity (Just et al., 1989). Treatment of intact cells with botulinum C2 toxin causes rounding up of cells, an effect which is accompanied by destruction of the microfilament network and an increase in the amount of the cellular G-actin (Reuner et al., 1987). A model explaining the toxin's action includes the following steps: At first the binding component of botulinum C2 toxin (C2II, 100 000 kDa) is proteolytically cleaved to an 88 kDa fragment which binds to the cell surface of the target cell thereby exposing an attachment site for the toxin component I. The enzymatically active component I, which is transfered into the cells by an unknown mechanism, ADP-ribosylates the cellular G-
DOI：
10.1007/978-1-60327-461-6_11
发表时间：
2009
期刊：
Methods in molecular biology (Clifton, N.J.)
影响因子：
--
作者：
Cassany, Aurelia;Gerace, Larry
通讯作者：
Gerace, Larry