Molecular structure of kanamycin nucleotidyltransferase determined to 3.0-A resolution
Molecular structure of kanamycin nucleotidyltransferase determined to 3.0-A resolution
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卡那霉素核苷酸转移酶的分子结构确定为 3.0-A 分辨率
DOI：
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
H. Holden
中科院分区：
文献类型：
--
作者：
J. Sakon;H. Liao;A. M. Kanikula;M. Benning;I. Rayment;H. Holden
卡那霉素核苷酸转移酶最初是从金黄色葡萄球菌中分离出来的，它通过催化核苷三磷酸(如三磷酸腺苷)中的核苷酸转移到氨基糖苷的4‘-羟基，从而使抗菌素卡那霉素失活。通过X-射线晶体分析确定了该酶的分子结构，其分辨率为3.0A。晶体属于P4(3)2(1)2空间群，晶胞尺寸为a=b=78.9A，c=219.2。7个重原子衍生物的电子密度图显示，以二聚体形式堆积在晶格中的分子呈现局部2倍旋转轴。随后的对称性平均化和溶剂平坦化提高了电子密度的质量，使得完全追踪253个氨基酸多肽链成为可能。每个单体都被分为两个不同的结构域：N-末端由残基Met 1-Glu 127组成，C-末端由残基Ala 128-Phe 253描绘。N-末端区域的特征是一个五链混合的β-折叠片层，而C-末端区域包含五个α-螺旋，其中四个形成了一个上下的α-螺旋束，与细胞色素c‘中观察到的非常相似。这两个亚基相互缠绕，形成一个椭球体，它有一个明显的裂隙，可以很容易地容纳各种已知与酶结合的氨基糖苷类化合物。
Kanamycin nucleotidyltransferase, as originally isolated from Staphylococcus aureus, inactivates the antibiotic kanamycin by catalyzing the transfer of a nucleotidyl group from nucleoside triphosphates such as ATP to the 4'-hydroxyl group of the aminoglycoside. The molecular structure of the enzyme described here was determined by X-ray crystallographic analysis to a resolution of 3.0 A. Crystals employed in the investigation belonged to the space group P4(3)2(1)2 with unit cell dimensions of a = b = 78.9 A and c = 219.2 A. An electron density map phased with seven heavy-atom derivatives revealed that the molecules packed in the crystalline lattice as dimers exhibiting local 2-fold rotation axes. Subsequent symmetry averaging and solvent flattening improved the quality of the electron density such that it was possible to completely trace the 253 amino acid polypeptide chain. Each monomer is divided into two distinct structural domains: the N-terminal motif composed of residues Met 1-Glu 127 and the C-terminal half delineated by residues Ala 128-Phe 253. The N-terminal region is characterized by a five-stranded mixed beta-pleated sheet whereas the C-terminal domain contains five alpha-helices, four of which form an up-and-down alpha-helical bundle very similar to that observed in cytochrome c'. The two subunits wrap about one another to form an ellipsoid with a pronounced cleft that could easily accommodate the various aminoglycosides known to bind to the enzyme.
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影响因子：
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作者：
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