Structure of ubiquitin-conjugating enzyme 9 displays significant differences with other ubiquitin-conjugating enzymes which may reflect its specificity for sumo rather than ubiquitin
Structure of ubiquitin-conjugating enzyme 9 displays significant differences with other ubiquitin-conjugating enzymes which may reflect its specificity for sumo rather than ubiquitin
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DOI：
10.1107/s0907444998002480
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发表时间：
1998-09-01
期刊：
影响因子：
--
通讯作者：
Naismith, JH
中科院分区：
文献类型：
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作者：
Giraud, MF;Desterro, JMP;Naismith, JH
泛素结合酶9（UbcB）的三维结构已经获得了2.8埃的分辨率，通过分子置换，然后结合自动化细化和图形干预。衍射数据记录在空间群P4（3）的单晶上，晶胞尺寸a = B = 73.9，c = 42.9埃。对于2.8埃的所有数据，最终模型的R因子为21.3%。只有N-末端甲硫氨酸、两个残基的N-末端延伸和四个残基的环未被最终的电子密度图定位。ubc 9是目前已知的第一个sumo，一种新的泛素样蛋白，结合酶，不结合泛素。Ubc 9的结构与已知的泛素结合酶的结构相比显示出重要的差异。在N-末端螺旋处，结构和序列比对由于一个氨基酸而不重合，从而与泛素缀合酶相比，给予Ubc 9不同的识别表面。这与远离催化位点的分子表面的静电表面的深刻变化相关联。这些差异在识别Sumo结合途径中的其他蛋白质方面可能是重要的。UbcB中的催化半胱氨酸具有带正电荷的唇和附近带负电荷的脊。这两个功能似乎仅限于相扑共轭酶，和相扑和泛素的序列比对表明，这些可能发挥作用，相扑/泛素歧视。
The three-dimensional structure of ubiquitin-conjugating enzyme 9 (UbcB) has been obtained to a resolution of 2.8 Angstrom by molecular replacement followed by a combination of automated refinement and graphical intervention. Diffraction data were recorded on a single crystal in space group P4(3) with cell dimensions a = b = 73.9, c = 42.9 Angstrom. The final model has an R factor of 21.3% for all data to 2.8 Angstrom. Only the N-terminal methionine, a two-residue N-terminal extension and a four-residue loop are not located by the final electron-density map. Ubc9 is now known to be the first sumo, a new ubiquitin-like protein, conjugating enzyme and does not conjugate ubiquitin. The structure of Ubc9 shows important differences compared with the structures of known ubiquitin-conjugating enzymes. At the N-terminal helix, the structural and sequence alignments are out of register by one amino acid giving Ubc9 a different recognition surface compared to ubiquitin-conjugating enzymes. This is coupled to a profound change in the electrostatic surface of the molecular face remote from the catalytic site. These differences may be important in recognition of other proteins in the Sumo conjugation pathway. The catalytic cysteine in UbcB has a positively charged lip and a negatively charged ridge nearby. Both these features seem confined to sumo-conjugating enzymes, and a sequence alignment of sumo and ubiquitin suggests how these might play a role in sumo/ubiquitin discrimination.