Stenberg Kaj A E, Vihinen Mauno
Faculty of Biosciences, Division of Biochemistry, University of Helsinki, Helsinki, Finland.
Proteins. 2009 May 15;75(3):748-59. doi: 10.1002/prot.22284.
We report the structure of a novel tetrameric form of the lactose repressor (LacI) protein from Escherichia coli refined to 2.1 A resolution. The tetramer is bound to 1.6-hexanediol present in the crystallization solution and the final R(free) for the structure is 0.201. The structure confirms previously reported structures on the monomer level. However, the tetramer is much more densely packed. This adds a new level of complexity to the interpretation of mutational effects and challenges details in the current model for LacI function. Several amino acids, previously associated with changes in function but unexplained at the structural level, appear in a new structural context in this tetramer which provides new implications for their function.
我们报道了来自大肠杆菌的乳糖阻遏蛋白（LacI）一种新型四聚体形式的结构，该结构精修至2.1埃分辨率。四聚体与结晶溶液中存在的1,6 -己二醇结合，该结构的最终R（游离）为0.201。该结构证实了先前在单体水平报道的结构。然而，四聚体的堆积更为紧密。这为突变效应的解释增加了新的复杂程度，并对当前LacI功能模型的细节提出了挑战。几个先前与功能变化相关但在结构水平上无法解释的氨基酸，在这个四聚体中出现在新的结构背景下，这为它们的功能提供了新的启示。
