Lee Yeon-Hee, Won Hyung-Sik, Lee Mann-Hyung, Lee Bong-Jin
Research Institute of Pharmaceutical Science, College of Pharmacy, Seoul National University, San 56-1, Shinlim-Dong, Kwanak-Gu, South Korea.
FEBS Lett. 2002 Jul 3;522(1-3):135-40. doi: 10.1016/s0014-5793(02)02919-8.
UreE, a urease accessory protein, is proposed to be a metallochaperone assisting the nickel incorporation into the urease active site. We investigated the effects of salt and nickel on the conformational stability of the UreE from Bacillus pasteurii (BpUreE), by circular dichroism (CD) and nuclear magnetic resonance spectroscopy accompanying a thermodynamic inspection. Far-UV CD spectra of BpUreE showed that both salt and nickel stabilized the ordered structure of the protein. The thermal denaturing of BpUreE showed a bimodal feature with an aggregation process before thermal unfolding. This thermally induced aggregation could be suppressed by the addition of salt up to 50 mM, and the further addition of salt increased the thermal resistance of the protein. The nickel addition also elevated the thermal resistance of BpUreE, although it could not prevent the aggregating process. Additionally, the stoichiometry of a specific nickel binding to BpUreE was revealed as one nickel per dimer. Altogether, the present results establish a rather detailed characterization of the thermostability and nickel-binding property of BpUreE.
脲酶辅助蛋白UreE被认为是一种金属伴侣蛋白，可协助镍离子掺入脲酶活性位点。我们通过圆二色光谱（CD）和核磁共振光谱，并结合热力学检测，研究了盐和镍对巴斯德芽孢杆菌UreE（BpUreE）构象稳定性的影响。BpUreE的远紫外CD光谱表明，盐和镍都能稳定蛋白质的有序结构。BpUreE的热变性呈现双峰特征，在热解折叠之前存在聚集过程。添加高达50 mM的盐可以抑制这种热诱导的聚集，进一步添加盐则会增加蛋白质的耐热性。添加镍也提高了BpUreE的耐热性，尽管它不能阻止聚集过程。此外，还揭示了与BpUreE特异性结合的镍的化学计量比为每个二聚体一个镍。总之，目前的结果对BpUreE的热稳定性和镍结合特性进行了相当详细的表征。
