Mori Mirko, Jiménez Beatriz, Piccioli Mario, Battistoni Andrea, Sette Marco
Magnetic Resonance Center (CERM) and Department of Chemistry, University of Florence, 50019 Sesto Fiorentino (FI), Italy, Department of Biology, University of Rome "Tor Vergata", 00133 Rome, Italy, National Institute of Biostructures and Biosystems (INBB), Viale delle Medaglie d'Oro 305, 00136 Rome, Italy, and Department of Chemical Science and Technology, University of Rome "Tor Vergata", 00133 Rome, Italy e-mail:
Biochemistry. 2008 Dec 9;47(49):12954-63. doi: 10.1021/bi801252e.
The structure of the SodCII-encoded monomeric Cu, Zn superoxide dismutase from Salmonella enterica has been solved by NMR spectroscopy. This represents the first solution structure of a natural and fully active monomeric superoxide dismutase in solution, providing information useful for the interpretation of the evolutional development of these enzymes. The protein scaffold consists of the characteristic beta-barrel common to the whole enzyme family. The general shape of the protein is quite similar to that of Escherichia coli Cu, Zn superoxide dismutase, although some differences are observed mainly in the active site. SodCII presents a more rigid conformation with respect to the engineered monomeric mutants of the human Cu, Zn superoxide dismutase, even though significant disorder is still present in the loops shaping the active site. The analysis of both dynamics and hydration properties of the protein in solution highlights the factors required to maintain the fully active and, at the same time, monomeric protein. This study provides novel insights into the functional differences between monomeric and dimeric bacterial Cu, Zn superoxide dismutases, in turn helping to explain the convergent evolution toward a dimeric structure in prokaryotic and eukaryotic enzymes of this class.
通过核磁共振光谱法解析了肠炎沙门氏菌中SodCII编码的单体铜锌超氧化物歧化酶的结构。这代表了溶液中天然且具有完全活性的单体超氧化物歧化酶的首个溶液结构，为解释这些酶的进化发展提供了有用信息。蛋白质支架由整个酶家族共有的特征性β桶组成。尽管主要在活性位点观察到一些差异，但该蛋白质的总体形状与大肠杆菌铜锌超氧化物歧化酶的形状非常相似。与人类铜锌超氧化物歧化酶的工程化单体突变体相比，SodCII呈现出更刚性的构象，尽管在塑造活性位点的环中仍存在明显的无序状态。对溶液中蛋白质的动力学和水合性质的分析突出了维持完全活性且同时保持单体状态的蛋白质所需的因素。这项研究为单体和二聚体细菌铜锌超氧化物歧化酶之间的功能差异提供了新的见解，进而有助于解释这类原核和真核酶向二聚体结构的趋同进化。
