The structure of human 5′-deoxy-5′-methylthioadenosine phosphorylase at 1.7 Å resolution provides insights into substrate binding and catalysis
The structure of human 5′-deoxy-5′-methylthioadenosine phosphorylase at 1.7 Å resolution provides insights into substrate binding and catalysis
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DOI：
10.1016/s0969-2126(99)80084-7
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发表时间：
1999-06-15
期刊：
影响因子：
5.7
通讯作者：
Ealick, SE
中科院分区：
文献类型：
--
作者：
Appleby, TC;Erion, MD;Ealick, SE
背景资料：5 '-脱氧-5'-甲硫基腺苷磷酸化酶（MTAP）催化5 '-脱氧-5'-甲硫基腺苷（MTA）可逆磷酸化为腺嘌呤和5-甲硫基-D-核糖-1-磷酸。MTA是多胺生物合成的副产物，其对于细胞生长和增殖是必需的。这种补救反应是人体细胞中游离腺嘌呤的主要来源。由于它的重要性，在耦合嘌呤补救途径多胺生物合成MTAP是一个潜在的化疗target.Results：我们已经确定了MTAP的晶体结构在1.7埃分辨率使用多波长异常衍射相位技术。MTAP是由三个相同亚基组成的三聚体。每个亚基由单个alp结构域组成，该结构域包含中央八链混合β折叠、较小的五链混合β折叠和六个α螺旋。天然结构显示嘌呤结合位点存在腺嘌呤分子。MTAP的结构与甲基硫代腺苷和硫酸根离子浸泡到活性site. Conclusions的衍射数据，以1.7埃resolution.Conclusions：整体的四级结构和亚基拓扑结构的MTAP是类似的哺乳动物嘌呤核苷磷酸化酶（PNP）。的MTAP-配体复合物的结构提供了一个地图的活性位点，并建议在底物结合和催化的特定残基的可能作用。还鉴定了MTAP和PNP之间底物特异性差异的残基。有关MTAP活性位点的结构和化学性质的详细信息将有助于合理设计这种潜在化疗靶点的抑制剂。MTAP结构代表哺乳动物PNP的第一个结构，其对6-氨基嘌呤具有特异性。
Background: 5'-Deoxy-5'-methylthioadenosine phosphorylase (MTAP) catalyzes the reversible phosphorolysis of 5'-deoxy-5'-methylthioadenosine (MTA) to adenine and 5-methylthio-D-ribose-1-phosphate. MTA is a by-product of polyamine biosynthesis, which is essential for cell growth and proliferation. This salvage reaction is the principle source of free adenine in human cells. Because of its importance in coupling the purine salvage pathway to polyamine biosynthesis MTAP is a potential chemotherapeutic target.Results: We have determined the crystal structure of MTAP at 1.7 Angstrom resolution using multiwavelength anomalous diffraction phasing techniques. MTAP is a trimer comprised of three identical subunits. Each subunit consists of a single alp domain containing a central eight-stranded mixed beta sheet, a smaller five-stranded mixed beta sheet and six a helices. The native structure revealed the presence of an adenine molecule in the purine-binding site. The structure of MTAP with methylthioadenosine and sulfate ion soaked into the active site was also determined using diffraction data to 1.7 Angstrom resolution.Conclusions: The overall quaternary structure and subunit topology of MTAP are similar to mammalian purine nucleoside phosphorylase (PNP). The structures of the MTAP-ligand complexes provide a map of the active site and suggest possible roles for specific residues in substrate binding and catalysis. Residues accounting for the differences in substrate specificity between MTAP and PNP are also identified. Detailed information about the structure and chemical nature of the MTAP active site will aid in the rational design of inhibitors of this potential chemotherapeutic target. The MTAP structure represents the first structure of a mammalian PNP that is specific for 6-aminopurines.