Structural Chemistry of Biomolecular Systems and Structu

RNaseIII家族的成员是基因表达的转录后调节因子。它们是双链(DS)RNA特异性内切核酸酶，其活性中心有一个签名基序，其产物中有一个2核苷酸3‘端的突出部分。虽然迪格尔目前是人们强烈兴趣的焦点，但结构更简单的细菌RNaseIII是整个家族的典范。在2001年首次对RNaseIII的活性中心进行了一瞥，并揭示了多年来其与dsRNA的非催化复合体的结构后，我们最近确定了RNaseIII产物复合体的结构。蛋白质-dsRNA相互作用的结构信息和RNaseIII处理dsRNA的机制可以外推到其他家族成员，包括Rnt1p、DROSHA和DICER。严格饥饿蛋白A(SSPA)是噬菌体P1裂解发育的转录激活剂，是稳定相诱导大肠杆菌耐酸所必需的。我们测定了鼠疫耶尔森氏菌SSPA(YP-SSPA)的晶体结构，它与大肠杆菌SSPA(EC-SSPA)的氨基酸序列有83%的同源性，在支持噬菌体P1的裂解生长和EC-SSPA突变体的耐酸性方面具有互补功能。结构分析表明，SSPA具有谷胱甘肽S转移酶(GST)的特征折叠。然而，SSPA缺乏GST活性，不结合谷胱甘肽。看来SSPA的表面口袋对于它的功能是重要的。口袋的大小、形状和性质表明它参与了蛋白质之间的相互作用。谷胱甘肽S转移酶(GST)催化谷胱甘肽与亲电化合物的结合。在癌前和肿瘤细胞中，特定形式的GST高水平表达，并参与细胞对抗癌药物的耐药。类pi GST(GSTP)在生物抗烷化剂方面具有特别重要的作用。旨在抑制GSTP以延长烷化剂疗效的治疗策略一直不成功，而GSTP激活的前药显示出巨大的潜力。我们已经开发了一种新型抗癌剂，它的功能是通过在癌细胞内释放一氧化氮来发挥作用。利用基于结构的方法，通过对一个先导化合物进行两次结构修饰，实现了GSTP的特异性。其他正在研发中的分子靶标/制剂包括叶酸和莽草酸途径酶以及病毒中和分子。

Members of the RNase III family are post-transcriptional regulators of gene expression. They are double-stranded (ds) RNA-specific endoribonucleases characterized by a signature motif in their active centers and a two-nucleotide 3' overhang in their products. While Dicer is currently the focus of intense interest, the structurally simpler bacterial RNase III serves as a paradigm for the entire family. After providing the first glimpse at the active center of RNase III in 2001 and revealing the architecture of its noncatalytic complexes with dsRNA over the years, we have recently determined the structure of RNase III-product complex. The structural information of protein-dsRNA interactions and the mechanism of dsRNA processing by RNase III can be extrapolated to other family members, including Rnt1p, Drosha, and Dicer. Stringent starvation protein A (SspA) is a transcriptional activator for the lytic development of phage P1 and is essential for stationary phase-induced acid tolerance in Escherichia coli. We have determined the crystal structure of Yersinia pestis SspA (Yp-SspA), which is 83% identical to E. coli SspA (Ec-SspA) in amino acid sequence and is functionally complementary in supporting the lytic growth of phage P1 and acid resistance of an Ec-SspA mutant. The structure reveals that SspA assumes the characteristic fold of glutathione S-transferase (GST). However, SspA lacks GST activity and does not bind glutathione. It appears that a surface pocket of SspA is important for its function. The size, shape, and property of the pocket suggest that it mediates protein-protein interactions. Glutathione S-transferase (GST) catalyzes glutathione conjugation with electrophilic compounds. In preneoplastic and neoplastic cells, specific forms of GST are expressed at high levels and to participate in the cells' resistance to anticancer drugs. Class pi GST (GSTP) is of particular importance in biological resistance to alkylating agents. Therapeutic strategies aimed at inhibiting GSTP to extend the efficacy of alkylating agents have been unsuccessful, whereas GSTP-activated prodrugs have shown great potential. We have developed a new type of anticancer agents, which function by releasing nitric oxide inside cancer cells. Using structure-based approach, GSTP specificity has been achieved with two structural modifications of a lead compound. Other molecular targets/agents in the pipeline include folate and shikimate pathway enzymes and virus-neutralizing molecules.