NMR studies of model peptides of PHGGGWGQ repeats within the N-terminus of prion proteins: a loop conformation with histidine and tryptophan in close proximity.
NMR studies of model peptides of PHGGGWGQ repeats within the N-terminus of prion proteins: a loop conformation with histidine and tryptophan in close proximity.
复制标题
朊病毒蛋白 N 末端 PHGGGWGQ 重复模型肽的 NMR 研究：组氨酸和色氨酸非常接近的环构象。
DOI：
10.1093/oxfordjournals.jbchem.a022750
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发表时间：
2000
影响因子：
2.7
通讯作者：
K. Hikichi
中科院分区：
文献类型：
--
作者：
H. Yoshida;N. Matsushima;Y. Kumaki;M. Nakata;K. Hikichi
人和小鼠朊病毒蛋白的N-末端区域含有5个串联重复序列，其共有序列为PHGGGWGQ。在水中对两种环肽进行NMR研究，环-[C（1）R（2）Q（3）P（4）H（5）G（6）G（7）S（8）W（9）G（10）Q（11）R（12）D（13）C（14）]（C1）和环-[C（1）R（2）D（3）P（4）H（5）G（6）G（7）G（8）W（9）G（10）Q（11）P（12）H（13）G（14）G（15）G（16）W（17）G（18）Q（19）R（20）D（21）C（22）]（C2），其通过N-和C-末端的Cys残基之间的二硫桥环化，以及其通过还原形成的相应线性肽（L1和L2）。这四种肽模拟物的C（α）H化学位移差异的模式与其他研究人员报道的人朊病毒蛋白串联重复序列中观察到的模式非常相似。在H5的C（β）H和L1的W 9侧链的质子之间发现了中程NOE连接性。在L2的H5-W 9和H13-W17中也观察到相应的NOE，但不明确。这些观察结果表明组氨酸（i）与色氨酸（i+4）非常接近。在L1和L2的W 9和Q11之间观察到d（alphaN）（i，i+2）NOE连接，并且在L1和L2的G10-Q11和L2的G18-Q19中也观察到d（NN）（i，i+1）NOE连接。获得了L2和C2的Q11和Q19的酰胺质子化学位移的显著较低的温度系数。L1的结构计算表明，HGG（G/S）W和（G/S）WGQ分别采用环状构象和β-转角。这些结果有力地表明朊病毒蛋白内的串联重复序列采用非随机结构。
The N-terminal region of the prion protein from human and mouse contains five tandem repeats with the consensus sequence of PHGGGWGQ. NMR studies were performed in water for two cyclic peptides, cyclo-[C(1)R(2)Q(3)P(4)H(5)G(6)G(7)S(8)W(9)G(10)Q(11)R(12)D(13)C(14)] (C1) and cyclo-[C(1)R(2)D(3)P(4)H(5)G(6)G(7)G(8)W(9)G(10)Q(11)P(12)H(13)G(14)G (15)G(16)W(17)G(18)Q(19)R(20)D(21)C(22)] (C2), which are cyclized by a disulfide bridge between the Cys residues at the N- and C-termini, and for their corresponding linear peptides (L1 and L2) which are formed by reduction. The patterns of the C(alpha)H chemical shift difference of these four peptide mimetics were very similar to those observed for the tandem repeats of human prion protein reported by other researchers. The medium-range NOE connectivities were found between the C(beta)H of the H5 and the proton of the W9 side chain for L1. The corresponding NOEs were also observed in H5-W9 and H13-W17 of L2 with ambiguity. These observations indicate that histidine (i) is in close proximity to tryptophan (i+4). d(alphaN) (i,i+2) NOE connectivities were observed between W9 and Q11 of L1 and L2, and d(NN) (i,i+1) NOE connectivities were also observed for G10-Q11 of L1 and L2 and for G18-Q19 of L2. Significantly lower temperature coefficients of amide proton chemical shifts were obtained for Q11 and Q19 of L2 and C2. Structure calculations for L1 showed that HGG(G/S)W and (G/S)WGQ adopt a loop conformation and a beta-turn, respectively. These results strongly suggest that the tandem repeats within prion protein adopt a non-random structure.