Eberstadt M, Grdadolnik S G, Gemmecker G, Kessler H, Buhr A, Erni B
Institut für Organische Chemie und Biochemie, Technische Universität München, Germany.
Biochemistry. 1996 Sep 3;35(35):11286-92. doi: 10.1021/bi960492l.
The structure of the IIBGlc domain of the Escherichia coli transporter for glucose was determined by multidimensional heteronuclear NMR. The glucose transporter (IICBGlc) belongs to the bacterial phosphotransferase system. It mediates uptake with concomittant phosphorylation of glucose. The N-terminal IICGlc domain spans the membrane, the C-terminal IIBGlc domain (residues 386-477) contains the phosphorylation site, Cys421. The structure of the subclonal IIB domain was determined based on 927 conformational constraints, including 744 NOE derived upper bounds, 43 constraints of ranges of dihedral angles based on measurements of vicinal coupling constants, and 70 upper and lower bound constraints associated with 35 hydrogen bonds. The distance geometry interpretation of the NMR data is based on the previously published sequence-specific 1H, 15N, and 13C resonance assignments [Golic Grdadolnik et al. (1994) Eur. J. Biochem. 219, 945-952]. The sequence of the secondary structure elements of IIB is alpha 1 beta 1 beta 2 alpha 2 beta 3 beta 4 alpha 3. The basic fold consists of a split alpha/beta-sandwich composed of an antiparallel sheet with strand order beta 1 beta 2 beta 4 beta 3 and three alpha-helices superimposed onto one side of the sheet. The hydrophobic helix alpha 1 is packed against helices alpha 2, alpha 3, and the beta-sheet. The phosphorylation site (Cys421) is at the end of beta 1 on the solvent-exposed face of the sheet surrounded by Asp419, Thr423 Arg424, Arg426, and Gln456 which are invariant in 15 homologous IIB domains from other PTS transporters.
通过多维异核核磁共振确定了大肠杆菌葡萄糖转运蛋白IIBGlc结构域的结构。葡萄糖转运蛋白（IICBGlc）属于细菌磷酸转移酶系统。它介导葡萄糖的摄取并伴随其磷酸化。N端的IICGlc结构域跨膜，C端的IIBGlc结构域（残基386 - 477）包含磷酸化位点Cys421。基于927个构象约束确定了亚克隆IIB结构域的结构，包括744个源自NOE的上限、基于邻位耦合常数测量的43个二面角范围约束以及与35个氢键相关的70个上下限约束。NMR数据的距离几何解释基于先前发表的序列特异性1H、15N和13C共振归属[Golic Grdadolnik等人（1994年），《欧洲生物化学杂志》219卷，945 - 952页]。IIB二级结构元件的序列为α1β1β2α2β3β4α3。基本折叠由一个分裂的α/β三明治组成，它由一个具有β1β2β4β3链序的反平行片层和叠加在片层一侧的三个α螺旋组成。疏水螺旋α1靠在螺旋α2、α3和β片层上。磷酸化位点（Cys421）位于片层溶剂暴露面β1的末端，周围是Asp419、Thr423、Arg424、Arg426和Gln456，这些在来自其他磷酸转移酶系统转运蛋白的15个同源IIB结构域中是不变的。
