Pedone F, Bonincontro A, Briganti G, Giansanti A, Londei P, Risuleo G, Mengoni M
Dipartimento di Genetica e Biologia Molecolare, Università degli Studidi Roma La Sapienza, Rome, Italy.
Biochim Biophys Acta. 1997 Jun 6;1335(3):283-9. doi: 10.1016/s0304-4165(96)00146-8.
The structural response of the ribosomes of the extremely thermophilic archaeon Sulfolobus solfataricus was analysed and compared to that of the mesophilic (E. coli) ribosomes by assaying ethidium bromide (EB) binding to the native 70S particles as a function of magnesium concentration. We found that the thermophilic ribosomes bound more EB than their mesophilic counterparts; on the other hand, inhibition of EB binding by Mg2+ ions was more effective in the E. coli 70S particle. In Sulfolobus, the separated 30S and 50S subunits and the 70S particle bound the drug in a similar fashion, whereas the E. coli 70S had a reduced number of binding sites with respect to the subunits. Light scattering measurements as a function of Mg2+ concentration were carried out at various temperatures to study the interaction between the ribosomal subunits from the thermophilic and the mesophilic bacteria. As expected, the association of ribosomal subunits in E. coli was magnesium dependent and could be observed also at low temperature. By contrast, the interaction between Sulfolobus ribosomal subunits was obligatorily dependent upon both magnesium ions and a temperature of at least 80 degrees C, close to the physiological optimum for cell growth (87 degrees C).
通过测定溴化乙锭（EB）与天然70S颗粒的结合情况作为镁离子浓度的函数，分析了极端嗜热古菌嗜热栖热菌核糖体的结构响应，并与嗜温（大肠杆菌）核糖体进行了比较。我们发现嗜热核糖体比嗜温核糖体结合更多的EB；另一方面，Mg2+离子对EB结合的抑制在大肠杆菌70S颗粒中更有效。在嗜热栖热菌中，分离的30S和50S亚基以及70S颗粒以相似的方式结合药物，而大肠杆菌70S相对于亚基的结合位点数量减少。在不同温度下进行了作为Mg2+浓度函数的光散射测量，以研究嗜热菌和嗜温菌核糖体亚基之间的相互作用。正如预期的那样，大肠杆菌核糖体亚基的缔合依赖于镁离子，并且在低温下也可以观察到。相比之下，嗜热栖热菌核糖体亚基之间的相互作用必然依赖于镁离子和至少80摄氏度的温度，接近细胞生长的生理最佳温度（87摄氏度）。
