Probing the non-native H helix translocation in apomyoglobin folding intermediates.
Probing the non-native H helix translocation in apomyoglobin folding intermediates.
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DOI：
10.1021/bi500478m
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发表时间：
2014-06-17
期刊：
影响因子：
2.9
通讯作者：
Wright PE
中科院分区：
文献类型：
--
作者：
Aoto PC;Nishimura C;Dyson HJ;Wright PE
脱辅基肌红蛋白通过A、B、G和H螺旋区快速塌陷形成的连续螺旋中间体折叠。在接近pH 4时形成具有类似结构的平衡熔融球。先前的研究表明，折叠中间体是动力学捕获状态，其中折叠受到G和H螺旋的非天然包装的阻碍。半胱氨酸残基在G和H螺旋的几个位置引入突变蛋白的荧光光谱显示W14荧光的差异淬灭，提供了动力学和平衡中间体中H螺旋相对于螺旋A和G易位的直接证据。Förster共振能量转移测量表明，与K140 C（螺旋H）偶联的5-（{2-[（乙酰基）氨基]乙基}氨基）萘-1-磺酸受体在平衡熔融球中比在天然状态下更接近Trp 14（螺旋A），其距离与H螺旋在N-末端方向上滑动约一个螺旋圈一致。S108 C-L135 C二硫化物的形成通过将G和H螺旋锁定到它们的天然寄存器中来防止H螺旋在平衡熔融球中的易位。通过加强天然包装的A，G，和H螺旋，二硫化物解决当地充满活力的挫折，并促进短暂对接的E螺旋区域的疏水核心，但只有一个小的影响的重折叠率。脱辅基肌红蛋白折叠的景观是高度崎岖的，有几个充满活力的瓶颈，挫败折叠;救济的任何一个主要的确定的瓶颈是不够的，以加快进展到过渡状态。
Apomyoglobin folds via sequential helical intermediates that are formed by rapid collapse of the A, B, G, and H helix regions. An equilibrium molten globule with a similar structure is formed near pH 4. Previous studies suggested that the folding intermediates are kinetically trapped states in which folding is impeded by non-native packing of the G and H helices. Fluorescence spectra of mutant proteins in which cysteine residues were introduced at several positions in the G and H helices show differential quenching of W14 fluorescence, providing direct evidence of translocation of the H helix relative to helices A and G in both the kinetic and equilibrium intermediates. Förster resonance energy transfer measurements show that a 5-({2-[(acetyl)amino]ethyl}amino)naphthalene-1-sulfonic acid acceptor coupled to K140C (helix H) is closer to Trp14 (helix A) in the equilibrium molten globule than in the native state, by a distance that is consistent with sliding of the H helix in an N-terminal direction by approximately one helical turn. Formation of an S108C–L135C disulfide prevents H helix translocation in the equilibrium molten globule by locking the G and H helices into their native register. By enforcing nativelike packing of the A, G, and H helices, the disulfide resolves local energetic frustration and facilitates transient docking of the E helix region onto the hydrophobic core but has only a small effect on the refolding rate. The apomyoglobin folding landscape is highly rugged, with several energetic bottlenecks that frustrate folding; relief of any one of the major identified bottlenecks is insufficient to speed progression to the transition state.
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DOI：
10.1038/nsb0796-613
发表时间：
1996-07-01
期刊：
NATURE STRUCTURAL BIOLOGY
影响因子：
--
作者：
Jamin, M;Baldwin, RL
通讯作者：
Baldwin, RL
影响因子：
5.6
作者：
GRIKO, YV;PRIVALOV, PL;KUTYSHENKO, VP
通讯作者：
KUTYSHENKO, VP
DOI：
10.1038/nsb1095-865
发表时间：
1995-10-01
期刊：
NATURE STRUCTURAL BIOLOGY
影响因子：
--
作者：
BALBACH, J;FORGE, V;DOBSON, CM
通讯作者：
DOBSON, CM
影响因子：
5.6
作者：
Cavagnero, S;Dyson, HJ;Wright, PE
通讯作者：
Wright, PE
DOI：
10.1038/nsb0596-439
发表时间：
1996-05-01
期刊：
NATURE STRUCTURAL BIOLOGY
影响因子：
--
作者：
Kay, MS;Baldwin, RL
通讯作者：
Baldwin, RL