New ice-binding face for type I antifreeze protein
New ice-binding face for type I antifreeze protein
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DOI：
10.1016/s0014-5793(99)01588-4
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发表时间：
1999-12-10
期刊：
影响因子：
3.5
通讯作者：
Davies, PL
中科院分区：
文献类型：
--
作者：
Baardsnes, J;Kondejewski, LH;Davies, PL
来自比目鱼的I型抗冻蛋白（AFP）是富含丙氨酸的37个氨基酸的单α-螺旋，其包含三个11个氨基酸的重复（Thr-X-2-Asx-X-7），其中X通常是Ala。规则间隔的Thr、Asx和Leu残基位于螺旋的一面，传统上被认为与冰表面形成氢键和货车范德华相互作用。最近，替代实验对Leu和Asn对冰结合的重要性提出了质疑。对5种Ⅰ型AFP亚型的序列比对表明，Leu和Asn不太保守，而与Thr相邻的Ala残基（与富含Leu/Asn的面成直角）则完全保守。为了研究这些Ala残基的作用，在螺旋周围的不同点上进行了一系列Ala到Leu的空间突变。所有取代的肽都是完整的，α-螺旋的，并在溶液中保持为单体。野生型活性保留在A19 L和A20 L中。A17 L，其中取代位于邻近的Thr丰富的面，没有检测到的抗冻活性，附近的A21 L取代有10%的野生型活性，并表现出弱的相互作用与冰面。我们提出了一个新的冰结合面的I型AFP，包括保守的丙氨酸丰富的表面和相邻的Thr，（C）1999年欧洲生物化学学会联合会。
Type I antifreeze protein (AFP) from winter flounder is an alanine-rich, 37 amino acid, single alpha-helix that contains three 11 amino acid repeats (Thr-X-2-Asx-X-7), where X is generally Ala. The regularly spaced Thr, Asx and Leu residues lie on one face of the helix and have traditionally been thought to form hydrogen bonds and van der Waals interactions with the ice surface. Recently, substitution experiments have called into question the importance of Leu and Asn for ice-binding. Sequence alignments of five type I AFP isoforms show that Leu and Asn are not well conserved, whereas Ala residues adjacent to the Thr, at right angles to the Leu/Asn-rich face, are completely conserved, To investigate the role of these Ala residues, a series of Ala to Leu steric mutations mas made at various points around the helix. All the substituted peptides were full, alpha-helical and remained as monomers in solution. Wild-type activity was retained in A19L and A20L. A17L, where the substitution lies adjacent to the Thr-rich face, had no detectable antifreeze activity, The nearby A21L substitution had 10% wildtype activity and demonstrated weak interactions with the ice surface. We propose a new ice-binding face for type I AFP that encompasses the conserved Ala-rich surface and adjacent Thr, (C) 1999 Federation of European Biochemical Societies.