Bernini Andrea, Venditti Vincenzo, Spiga Ottavia, Ciutti Arianna, Prischi Filippo, Consonni Roberto, Zetta Lucia, Arosio Ivana, Fusi Paola, Guagliardi Annamaria, Niccolai Neri
Università degli Studi di Siena, Dipartimento di Biologia Molecolare, via A. Fiorentina 1, 53100 Siena, Italy.
Biophys Chem. 2008 Oct;137(2-3):71-5. doi: 10.1016/j.bpc.2008.07.003. Epub 2008 Jul 16.
Understanding how proteins are approached by surrounding molecules is fundamental to increase our knowledge of life at atomic resolution. Here, the surface accessibility of a multifunctional small protein, the archaeal protein Sso7d from Sulfolobus solfataricus, has been investigated by using TEMPOL and Gd(III)(DTPA-BMA) as paramagnetic probes. The DNA binding domain of Sso7d appears very accessible both to TEMPOL and Gd(III)(DTPA-BMA). Differences in paramagnetic attenuation profiles of (1)H-(15)N HSQC protein backbone amide correlations, observed in the presence of the latter paramagnetic probes, are consistent with the hydrogen bond acceptor capability of the N-oxyl moiety of TEMPOL to surface exposed Sso7d amide groups. By using the gadolinium complex as a paramagnetic probe a better agreement between Sso7d structural features and attenuation profile is achieved. It is interesting to note that the protein P-loop region, in spite of the high surface exposure predicted by the available protein structures, is not approached by TEMPOL and only partially by Gd(III)(DTPA-BMA).
了解蛋白质如何与周围分子相互作用对于我们在原子分辨率下增进对生命的认识至关重要。在此，通过使用TEMPOL和Gd(III)(DTPA - BMA)作为顺磁探针，对来自嗜热栖热菌的多功能小蛋白古菌蛋白Sso7d的表面可及性进行了研究。Sso7d的DNA结合结构域对TEMPOL和Gd(III)(DTPA - BMA)似乎都非常容易接近。在存在后一种顺磁探针的情况下观察到的(1)H-(15)N HSQC蛋白主链酰胺相关性的顺磁衰减谱差异，与TEMPOL的N-氧基部分与表面暴露的Sso7d酰胺基团的氢键受体能力一致。通过使用钆配合物作为顺磁探针，Sso7d的结构特征与衰减谱之间取得了更好的一致性。有趣的是，尽管现有蛋白质结构预测蛋白质P环区域具有高表面暴露性，但TEMPOL并未接近该区域，而Gd(III)(DTPA - BMA)仅部分接近该区域。
