Mapping of disulfide bridges in antifreeze proteins from overwintering larvae of the beetle Dendroides canadensis
Mapping of disulfide bridges in antifreeze proteins from overwintering larvae of the beetle Dendroides canadensis
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DOI：
10.1021/bi972853i
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发表时间：
1998-05-05
期刊：
影响因子：
2.9
通讯作者：
Duman, JG
中科院分区：
文献类型：
--
作者：
Li, N;Chibber, BAK;Duman, JG
已在某些高纬度海洋鱼类、昆虫和其他陆生节肢动物和植物中发现了抗冻蛋白 (AFP)。尽管结构差异很大，但它们的非依数抗冻活性的机制可能非常相似。 AFP 在首选生长位点与潜在晶种冰晶表面形成氢键，从而阻止晶体生长。来自加拿大 Dendroides canadensis 甲虫越冬幼虫的 AFP 是最活跃的 AFP 之一。这些 8.7 kDa 蛋白质由七个 12 或 13 聚体重复单元组成。它们最显着的特征是在整个长度中每六个残基就有一个半胱氨酸。因此，鉴定这些半胱氨酸的二硫键对于理解这些 AFP 的结构至关重要。这项研究表明，Dendroides AFP 中的所有 16 个 Cys 残基都是二硫键桥接的。所有 7 个 12 或 13 聚体重复序列均具有内部二硫键，并且在除第一个重复序列之外的所有重复序列中，重复序列第 1 和第 7 位的 Cys 残基均相连。在重复1中，位置1处的Cys与位置10处的Cys连接，而不是像其他重复中那样连接位置7处的Cys，并且第一个重复的位置7处的Cys与第二个重复的位置4处的Cys连接。二硫桥可能起到定位丝氨酸和苏氨酸残基的亲水性侧链的作用，以便它们与冰形成氢键。
Antifreeze proteins (AFPs) have been identified in certain high-latitude marine fish, insects and other terrestrial arthropods, and plants. Despite considerable structural variation, the mechanisms of their noncolligative antifreeze activity are probably quite similar. AFPs hydrogen bond onto the surface of potential seed ice crystals at preferred growth sites, thereby preventing growth of the crystals. AFPs from overwintering larvae of the beetle Dendroides canadensis are among the most active AFPs. These 8.7-kDa proteins consist of seven 12- or 13-mer repeating units. Their most striking feature is the location of cysteines every six residues throughout their length. Consequently, identification of the disulfide linkages of these cysteines is essential to understanding the structure of these AFPs, This study demonstrated that all of the 16 Cys residues in the Dendroides AFPs are disulfide bridged. All of the seven 12- or 13-mer repeats have internal disulfide bridges, and in all but the first repeat the Cys residues at positions 1 and 7 of the repeats are linked. In repeat 1 the Cys at position 1 is linked to the Cys at position 10, rather than the Cys at position 7 as in the other repeats, and the Cys at position 7 of the first repeat is linked to a Cys at position 4 of the second repeat. The disulfide bridges probably function to position the hydrophilic side chains of serine and threonine residues so that they hydrogen bond with ice.