Solution structure of a recombinant type I sculpin antifreeze protein
Solution structure of a recombinant type I sculpin antifreeze protein
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DOI：
10.1021/bi047782j
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发表时间：
2005-02-15
期刊：
影响因子：
2.9
通讯作者：
Mackay, JP
中科院分区：
文献类型：
--
作者：
Kwan, AHY;Fairley, K;Mackay, JP
我们已经在 278 K 和 268 K 测定了 rSS3 的溶液结构，rSS3 是 I 型短角杜父父鱼抗冻蛋白 (AFP) 的重组形式。该 AFP 包含不寻常的 N 末端残基序列，以及 I 型冬鲽 AFP 特有的 11 个残基重复序列中的两个。杜父鱼 AFP N 端区域的溶液构象被认为是导致杜父父父鱼和比目鱼 AFP 识别不同冰面的关键因素。在 278 K 时，rSS3 中的两个重复单元（残基 11-20 和 21-32）形成连续的 α-螺旋，第二个重复中的残基 30-33 的定义稍差。在 N 末端区域内，残基 2-6 轮廓分明且呈螺旋状，并通过包含残基 A7-T11 的更灵活的区域连接至主螺旋。在 268 K 时，AFP 总体上呈螺旋状，但保留了明显的铰链区域。两个重复单元的螺旋构象与I型冬鲽AFP中的相应重复单元几乎相同。我们还表明，虽然四乙酰化的 rSS3 具有与天然 AFP 相当的抗冻活性，但其整体结构与未乙酰化的肽相同。这些数据为抗冻活性的结构决定因素提供了一些见解，并有助于开发模型来解释杜父父父鱼和比目鱼 I 型 AFP 对不同冰界面的识别。
We have determined the solution structure of rSS3, a recombinant form of the type I shorthorn sculpin antifreeze protein (AFP), at 278 and 268 K. This AFP contains an unusual sequence of N-terminal residues, together with two of the 11-residue repeats that are characteristic of the type I winter flounder AFP. The solution conformation of the N-terminal region of the sculpin AFP has been assumed to be the critical factor that results in recognition of different ice planes by the sculpin and flounder AFPs. At 278 K, the two repeats units (residues 11-20 and 21-32) in rSS3 form a continuous a.-helix, with the residues 30-33 in the second repeat somewhat less well defined. Within the N-terminal region, residues 2-6 are well defined and helical and linked to the main helix by a more flexible region comprising residues A7-T11. At 268 K the AFP is overall more helical but retains the apparent hinge region. The helical conformation of the two repeats units is almost identical to the corresponding repeats in the type I winter flounder AFP. We also show that while tetracetylated rSS3 has antifreeze activity comparable to the natural AFP, its overall structure is the same as that of the unacetylated peptide. These data provide some insight into the structural determinants of antifreeze activity and should assist in the development of models that explain the recognition of different ice interfaces by the sculpin and flounder type I AFPs.