Structure and dynamics of bacteriophage IKe major coat protein in MPG micelles by solution NMR.
Structure and dynamics of bacteriophage IKe major coat protein in MPG micelles by solution NMR.
复制标题
通过溶液 NMR 分析 MPG 胶束中噬菌体 IKe 主要外壳蛋白的结构和动力学。
作者：
K. Williams;N. Farrow;C. Deber;L. Kay
使用多核溶液核磁共振波谱对完全质子化的肉豆蔻酰磷脂酰甘油 (MPG) 胶束中 53 个残基的丝状噬菌体 IKe 主要外壳蛋白的结构和动力学进行了表征。洗涤剂溶解的外壳蛋白[序列：见文本]模仿了外壳蛋白的膜结合“组装中间体”形式，这种形式发生在噬菌体生命周期的一部分中。 IKe 外壳蛋白的 NMR 研究表明，外壳蛋白主要是 α 螺旋，表现出长的两亲性表面。螺旋（Asn 4 到 Ser 26）和一个较短的“胶束跨越”C 端螺旋，从 TRP 29 开始，至少延续到 Phe 48。Pro 30 可能出现在 C 端螺旋的第一圈，考虑到该残基所施加的氢键和空间限制，它位于理想的位置。大部分 N 末端螺旋和所有 TM 螺旋之间 15N 弛豫值（T1、T2 和 NOE 以及 500 MHz 和 T2 在 600 MHz）的相似性表明，N 末端螺旋与 TM 螺旋一样与胶束密切相关。对胶束中蛋白质的描述得到了对 asn 8 和 Ser 50 之间溶血脂质子和蛋白质酰胺质子之间 NOE 的观察的支持。N 末端和 TM 螺旋在微秒到秒时间尺度上表现出显着的移动性，这可能反映了两个螺旋之间方向的变化。总体研究结果有助于阐明TM α螺旋中各个残基的作用，并提供对外壳蛋白的二级结构、动力学以及水和胶束环境的理解。
The structure and dynamics of the 53-residue filamentous bacteriophage IKe major coat protein in fully protonated myristoyllysophosphatidylglycerol (MPG) micelles were characterized using multinuclear solution NMR spectroscopy. Detergent-solubilized coat protein [sequence: see text] mimics the membrane-bound "assembly intermediate" form of the coat protein which occurs during part of the phage life cycle. NMR studies of the IKe coat protein show that the coat protein is largely alpha-helical, exhibiting a long amphipathic surface. helix (Asn 4 to Ser 26) and a shorter "micelle-spanning" C-terminal helix which begins at TRP 29 and continues at least to Phe 48. Pro 30 likely occurs in the first turn of the C-terminal helix, where it is ideally situated given the hydrogen bonding and steric restrictions imposed by this residue. The similarity of 15N relaxation values (T1, T2, and NOE and 500 MHz and T2 at 600 MHz) among much of the N-terminal helix and all of the TM helix indicates that the N-terminal helix is as closely associated with the micelle as the TM helix. The description of the protein in the micelle is supported by the observation of NOEs between lysolipid protons and protein amide protons between asn 8 and Ser 50. The N-terminal and TM helices exhibit substantial mobility on the microsecond to second time scale, which likely reflects changes in the orientation between the two helices. The overall findings serve to clarify the role of individual residues in the context of a TM alpha-helix and provide an understanding of the secondary structure, dynamics, and aqueous and micellar environments of the coat protein.