Estébanez-Perpiña E, Fuentes-Prior P, Belorgey D, Braun M, Kiefersauer R, Maskos K, Huber R, Rubin H, Bode W
Abteilung für Strukturforschung, Max-Planck-Institut für Biochemie, Planegg-Martinsried, Germany.
Biol Chem. 2000 Dec;381(12):1203-14. doi: 10.1515/BC.2000.148.
Granzyme B is the prototypic member of the granzymes, a family of trypsin-like serine proteinases localized in the dense cytoplasmic granules of activated natural killer cells and cytotoxic T lymphocytes. Granzyme B directly triggers apoptosis in target cells by activating the caspase pathway, and has been implicated in the etiology of rheumatoid arthritis. Human granzyme B expressed in a baculovirus system has been crystallized without inhibitor and its structure has been determined to 3.1 A resolution, after considerably improving the diffraction power of the crystals by controlled humidity changes. The granzyme B structure reveals an overall fold similar to that found in cathepsin G and human chymase. The guanidinium group of Arg226, anchored at the back of the S1-specificity pocket, can form a salt bridge with the P1-Asp side chain of a bound peptide substrate. The architecture of the substrate binding site of granzyme B appears to be designed to accommodate and cleave hexapeptides such as the sequence Ile-Glu-Thr-Asp-/Ser-Gly present in the activation site of pro-caspase-3, a proven physiological substrate of granzyme B. These granzyme B crystals, with fully accessible active sites, are well suited for soaking with small synthetic inhibitors that might be used for a treatment of chronic inflammatory disorders.
颗粒酶B是颗粒酶家族的典型成员，颗粒酶是一类胰蛋白酶样丝氨酸蛋白酶，定位于活化的自然杀伤细胞和细胞毒性T淋巴细胞的致密胞质颗粒中。颗粒酶B通过激活半胱天冬酶途径直接触发靶细胞凋亡，并与类风湿性关节炎的病因有关。在杆状病毒系统中表达的人颗粒酶B在没有抑制剂的情况下结晶，并且在通过控制湿度变化显著提高晶体的衍射能力后，其结构已被确定为3.1埃分辨率。颗粒酶B的结构揭示了一种与组织蛋白酶G和人糜酶中发现的总体折叠相似的结构。位于S1特异性口袋后部的Arg226的胍基可以与结合的肽底物的P1-Asp侧链形成盐桥。颗粒酶B的底物结合位点的结构似乎被设计成容纳和切割六肽，例如存在于前半胱天冬酶-3激活位点的序列Ile-Glu-Thr-Asp-/Ser-Gly，这是颗粒酶B已证实的生理底物。这些具有完全可及活性位点的颗粒酶B晶体非常适合用可能用于治疗慢性炎症性疾病的小合成抑制剂进行浸泡。
