Reiling K K, Pray T R, Craik C S, Stroud R M
Departments of Biochemistry & Biophysics and Pharmaceutical Chemistry, and Graduate Group in Biophysics, University of California in San Francisco, San Francisco, California 94143, USA.
Biochemistry. 2000 Oct 24;39(42):12796-803. doi: 10.1021/bi001019h.
The structure of Kaposi's sarcoma-associated herpesvirus protease (KSHV Pr), at 2.2 A resolution, reveals the active-site geometry and defines multiple possible target sites for drug design against a human cancer-producing virus. The catalytic triad of KSHV Pr, (Ser114, His46, and His157) and transition-state stabilization site are arranged as in other structurally characterized herpesviral proteases. The distal histidine-histidine hydrogen bond is solvent accessible, unlike the situation in other classes of serine proteases. As in all herpesviral proteases, the enzyme is active only as a weakly associated dimer (K(d) approximately 2 microM), and inactive as a monomer. Therefore, both the active site and dimer interface are potential targets for antiviral drug design. The dimer interface in KSHV Pr is compared with the interface of other herpesviral proteases. Two conserved arginines (Arg209), one from each monomer, are buried within the same region of the dimer interface. We propose that this conserved arginine may provide a destabilizing element contributing to the tuned micromolar dissociation of herpesviral protease dimers.
卡波西肉瘤相关疱疹病毒蛋白酶（KSHV Pr）的结构在2.2埃分辨率下得以揭示，其展现了活性位点的几何结构，并确定了针对一种能引发人类癌症的病毒进行药物设计的多个可能靶点。KSHV Pr的催化三联体（Ser114、His46和His157）以及过渡态稳定位点的排列方式与其他已进行结构表征的疱疹病毒蛋白酶相同。与其他类别的丝氨酸蛋白酶不同，远端组氨酸-组氨酸氢键可被溶剂接触。与所有疱疹病毒蛋白酶一样，该酶仅作为弱相关二聚体（解离常数K(d)约为2微摩尔）具有活性，作为单体则无活性。因此，活性位点和二聚体界面都是抗病毒药物设计的潜在靶点。将KSHV Pr中的二聚体界面与其他疱疹病毒蛋白酶的界面进行了比较。两个保守的精氨酸（Arg209），每个单体各有一个，埋藏在二聚体界面的同一区域内。我们提出，这种保守的精氨酸可能提供一个不稳定因素，有助于疱疹病毒蛋白酶二聚体以微摩尔级别的解离常数进行解离。
