Structural characterization of glycinamide-RNase-transformylase T from Mycobacterium tuberculosis
Structural characterization of glycinamide-RNase-transformylase T from Mycobacterium tuberculosis
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DOI：
10.1080/22221751.2019.1707716
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发表时间：
2020-01-01
影响因子：
13.2
通讯作者：
Jin, Qi
中科院分区：
文献类型：
--
作者：
Chen, Cong;Liu, Zuliang;Jin, Qi
结核分枝杆菌(Mtb)嘌呤挽救途径中的酶被认为是抗菌药物开发的一个有吸引力的靶点。虽然这一途径在结核分枝杆菌中尚未被广泛研究，但它已被认为是生长和生存所必需的。甘氨酰胺-核糖核酸酶-转换酶T(PUT)仅存在于包括Mtb在内的一些特定细菌中，它利用依赖于ATP的连接来催化5‘-磷酸核糖基-甘氨酰胺(GAR)的甲酰化反应，在从头开始的嘌呤挽救途径的第三反应中。在本研究中，我们测定了MtbPurT的晶体结构，分辨率为2.79埃。与Horikoshii OT3Purt(PhBCCPPurT)不同的是，MtbPurT呈“开放”构象，导致更广泛的ATP结合口袋，从而可能促进辅因子的进出。此外，与E.coliPurt(EcPurT)的活性位点重叠表明，MtbPurT中涉及ATP结合位点的残基在结构上相似，但在琼脂结合位点上存在显著差异。MtbPurT的383-389环要短得多，并从GAR底物的磷酸盐移位5.7埃。不同的琼脂结合模式可能会导致MtbPurT的构象发生较大的变化，为抗结核药物的开发提供了可能。
Enzymes from the purine salvage pathway in Mycobacterium tuberculosis (Mtb) have been regarded as an attractive target for the development of anti-bacterial drugs. Although this pathway has not been extensively studied in Mtb, it has been identified as essential for growth and survival. Glycinamide-RNase-transformylase T (PurT) is found only in some specific bacteria including Mtb and utilizes ATP-dependent ligation to catalyze the formylation of 5 '-phosphoribosyl-glycinamide (GAR) in the third reaction of the de novo purine salvage pathway. In the study, we determined the crystal structure of MtbPurT at a resolution of 2.79 angstrom. In contrast to Pyrococcus horikoshii OT3 PurT (phBCCPPurT), MtbPurT exhibits an "open" conformation, which results in a broader ATP-binding pocket and thus might facilitate the entry and exit of the cofactor. Additionally, active site superposition with E.coli PurT (EcPurT) showed that residues involved in the ATP-binding site in MtbPurT exhibited structural similarity but had notable difference in the GAR-binding site. The loop 383-389 in MtbPurT was much shorter and shifted 5.7 angstrom away from the phosphate of the GAR substrate. The different GAR-binding mode might result in a large conformational change in MtbPurT, and would provide a possible opportunity for anti-TB drug development.