Nativelike structure and stability in a truncation mutant of a protein minidomain: the peripheral subunit-binding domain.
Nativelike structure and stability in a truncation mutant of a protein minidomain: the peripheral subunit-binding domain.
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蛋白质微型结构域截短突变体的天然结构和稳定性：外围亚基结合结构域。
DOI：
10.1021/bi982915k
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Raleigh,DP
中科院分区：
文献类型：
--
作者：
Spector,S;Young,P;Raleigh,DP
尽管它的尺寸小，从theBacillusstearothermophiluspyruvate脱氢酶多酶复合物的二氢硫辛酰胺乙酰转移酶组分的外围亚基结合域采用了独特的，紧凑的结构。为了确定该结构域是否需要完整的43个残基序列以采用稳定的天然样结构，制备了3种不同长度的蛋白质。psbd 41对应于结构域的残基3 - 43，psbd 36跨越残基6 - 41，psbd 33包含残基7 - 39。Psbd 41以合作的双态方式折叠，aTm为53 °C，25 °C下的稳定性为2.2 kcal mol-1。Psbd 36几乎同样稳定，aTm为48 °C，稳定性为1.8 kcal mol-1。相似的数值和热容量表明psbd 36和psbd 41的埋藏表面积大致相同。psbd 41和psbd 36之间CαH和NH化学位移的微小差异表明这两个序列采用相同的三级折叠。在每个残基的基础上，ΔH°和ΔC° p落在单结构域球状蛋白的典型范围内。psbd 33的稳定性明显较低。它在25 °C下不完全折叠，并且在所有温度下都显示出加宽的NMR谱线。ANS滴定提供的证据表明，这是由于类天然分子和未折叠分子之间的平衡，而不是形成熔融球。折叠的psbd 33分子部分似乎采用与全长结构域相同的结构。因此，虽然形成完全稳定的天然结构需要多于33个残基的核心，但折叠不需要整个序列。
Despite its small size, the peripheral subunit-binding domain from the dihydrolipoamide acetyltransferase component of theBacillusstearothermophiluspyruvate dehydrogenase multienzyme complex adopts a unique, compact structure. To determine whether the full 43 residue sequence is required for the domain to adopt a stable, nativelike structure, 3 proteins of different lengths were prepared. Psbd41 corresponds to residues 3−43 of the domain, psbd36 spans residues 6−41, and psbd33 comprises residues 7−39. Psbd41 folds in a cooperative, two-state fashion with aTmof 53 °C and a stability at 25 °C of 2.2 kcal mol-1. Psbd36 is nearly as stable with aTmof 48 °C and a stability of 1.8 kcal mol-1. Similarm-values and heat capacities suggest that psbd36 and psbd41 bury approximately the same surface area. Minimal differences in CαH and NH chemical shifts between psbd41 and psbd36 show that the two sequences adopt the same tertiary fold. On a per residue basis, ΔH° and ΔC°pfall within the range typical for single-domain globular proteins. Psbd33 is significantly less stable. It is not fully folded at 25 °C, and at all temperatures it shows broadened NMR lines. ANS titrations provide evidence that this is due to an equilibrium between nativelike and unfolded molecules rather than formation of a molten globule. The fraction of psbd33 molecules which are folded appear to adopt the same structure as the full-length domain. Thus, although more than the 33 residue core is required to form a fully stable native structure, the entire sequence is not required for folding.