Abe K, Watabe S, Emori Y, Watanabe M, Arai S
Department of Agricultural Chemistry, University of Tokyo, Japan.
FEBS Lett. 1989 Dec 4;258(2):297-300. doi: 10.1016/0014-5793(89)81678-3.
The ice nucleation active gene, inaA, of Erwinia ananas IN-10 has been sequenced. This gene encodes a protein composed of 1322 amino acid residues. The inaA protein contains a 1120-residue segment consisting of 70 repeats of closely related 16 amino acid motifs (R-domain), which is flanked by N- and C-terminal sequences (N- and C-domains, respectively). Its primary structure is similar to, but not identical with, those of Pseudomonas inaW and inaZ gene products. By truncating the inaA gene to various extents, it was found that deletion of the C-domain resulted in complete loss of the ice nucleation activity, whereas removal of the N-domain led to a moderate decrease in the activity. Complete loss of the activity was also observed when the N-domain plus a large part of the P-domain were deleted. It is suggested that the C-domain is required for the assembly of inaA protein to form a functional ice nucleus.
菠萝欧文氏菌IN-10的冰核活性基因inaA已被测序。该基因编码一种由1322个氨基酸残基组成的蛋白质。inaA蛋白包含一个由1120个残基组成的片段，该片段由70个紧密相关的16个氨基酸基序（R结构域）重复组成，其两侧分别是N端和C端序列（分别为N结构域和C结构域）。其一级结构与丁香假单胞菌inaW和inaZ基因产物的结构相似，但不完全相同。通过不同程度地截短inaA基因，发现C结构域的缺失导致冰核活性完全丧失，而N结构域的去除导致活性适度下降。当N结构域加上大部分P结构域被删除时，也观察到活性完全丧失。表明C结构域是inaA蛋白组装形成功能性冰核所必需的。
