Baslé A, Delcour A H
Department of Biology and Biochemistry, 369 Science & Research Building II, University of Houston, Houston, TX 77204, USA.
Biochem Biophys Res Commun. 2001 Jul 13;285(2):550-4. doi: 10.1006/bbrc.2001.5155.
Spermine, a polyamine based on a 12-carbon motif, is an effective inhibitor of E. coli OmpF porin. Here we study the inhibition of porin by two polyamine toxins commonly used as modulators of polyamine-sensitive channels: Philanthotoxin-433 (PhTX) from wasp venom and Joro spider toxin (JSTX). Both are highly asymmetric molecules, with at one end a 12-carbon chain polyamine targeting the molecule to the porin constriction zone, and at the other end large aromatic groups conferring to this extremity a size in the order of the OmpF constriction zone. Here we report that PhTX, but not Joro toxin, induces a high degree of flickering in the OmpF-mediated current. The effect is concentration and voltage-dependent, and greatly diminished in a mutant lacking D113 on the constriction loop, a residue previously shown to be required for spermine sensitivity. Possible reasons for the distinct sensitivity of OmpF to PhTX and Joro toxin are discussed.
精胺是一种基于12碳基序的多胺，是大肠杆菌外膜孔蛋白F（E. coli OmpF porin）的有效抑制剂。在此，我们研究了两种常用作多胺敏感通道调节剂的多胺毒素对孔蛋白的抑制作用：来自黄蜂毒液的 philanthotoxin - 433（PhTX）和Joro蜘蛛毒素（JSTX）。两者都是高度不对称的分子，一端是靶向孔蛋白收缩区的12碳链多胺，另一端是大的芳香基团，使该末端具有与OmpF收缩区相当的尺寸。在此我们报告，PhTX而非Joro毒素会在OmpF介导的电流中诱导高度的闪烁。这种效应具有浓度和电压依赖性，并且在收缩环上缺乏D113的突变体中大大减弱，先前已证明该残基是精胺敏感性所必需的。文中讨论了OmpF对PhTX和Joro毒素敏感性不同的可能原因。
