Jursch R, Hildebrand A, Hobom G, Tranum-Jensen J, Ward R, Kehoe M, Bhakdi S
Institute of Medical Microbiology, University of Mainz, Germany.
Infect Immun. 1994 Jun;62(6):2249-56. doi: 10.1128/iai.62.6.2249-2256.1994.
Chemical modification of histidine residues in staphylococcal alpha-toxin leads to loss of functional activity. Site-directed mutants of the toxin in which each of the four histidine residues was replaced by several amino acids were therefore produced. The mutant proteins were purified and characterized. Exchange of H-259 or H-144 was sometimes tolerated without reduction in hemolytic activity. These histidine residues are thus not essential for toxin function. Exchange of H-35 and H-48, however, had marked effects. H-35 mutant toxins bound with high affinity to rabbit erythrocytes but displayed faulty oligomerization and were unable to form pores. H-48 mutant toxins also had severely impaired hemolytic activity due probably to faulty hexamerization. We interpret these results to indicate that the N-terminal domain of alpha-toxin in the region of H-35 and H-48 is involved in protomer-protomer interactions that underlie the hexamerization and pore-forming process.
葡萄球菌α-毒素中组氨酸残基的化学修饰导致功能活性丧失。因此，制备了毒素的定点突变体，其中四个组氨酸残基中的每一个都被几种氨基酸取代。对突变蛋白进行了纯化和表征。H-259或H-144的交换有时可以耐受，而溶血活性不会降低。因此，这些组氨酸残基对于毒素功能不是必需的。然而，H-35和H-48的交换有显著影响。H-35突变毒素与兔红细胞具有高亲和力结合，但显示出错误的寡聚化，并且无法形成孔。H-48突变毒素的溶血活性也严重受损，这可能是由于错误的六聚化所致。我们将这些结果解释为表明在H-35和H-48区域的α-毒素的N末端结构域参与了六聚化和孔形成过程所基于的原体-原体相互作用。
