Wu C H, Lee M F, Liao S C, Luo S F
Department of Medical Research, Taichung Veterans General Hospital, Taiwan 40705.
J Biol Chem. 1996 Jul 26;271(30):17937-43. doi: 10.1074/jbc.271.30.17937.
A previous article described the isolation of several lambdagt22A cDNA clones expressing the American cockroach (Periplaneta americana) Cr-PI allergens recognized by both human atopic IgE antibodies and anti-Cr-PI monoclonal antibodies (Wu, C. H., Lee, M. F., and Liao, S. C.(1995) J. Allergy Clin. Immunol. 96, 352-359). This article presents the nucleotide and deduced amino acid sequences of two cDNA clones encoding major allergens of P. americana. Clones C12 and C20 encode proteins of 685 and 631 amino acids with two potential N-glycosylation sites each. The predicted molecular weights for C12 and C20 cloned proteins are 79,300 and 75, 500 with isoelectric point values of 6.26 and 6.63, which are compatible with the determined sizes (Mr 78,000 and 72,000) and isoelectric point value (6.2) of the Cr-PI allergens of P. americana. A high degree of identity (69.1%), including several overlapped predicted central antigenic determinant residues, was found between two allergens. The anti-fusion protein antibody-based enzyme-linked immunosorbent assay was able to detect crude American cockroach extract, Cr-PI, recombinant proteins, and commercial cockroach extracts, which provides further evidence that two allergens share common antigen determinants. Recombinant allergens of clones C12 and C20 both showed 47.4% skin reactivities on 19 cockroach-sensitive asthmatic patients. Unexpectedly, although no sequence similarity was found to other known allergens, two aromatic amino acid-rich allergens were found to have a striking sequence identity to insect storage proteins (20.1-33.9%), insect juvenile hormone-suppressible proteins (30.9-36.4%), and arthropod hemocyanins (29.7-34.6%). Results suggested that two prominent allergens of P. americana are ancestrally related to these insect hemolymph proteins and represent a new group of proteins in the hemocyanin superfamily. These data will now facilitate epitope-mapping studies, and the recombinant allergens may be valuable for diagnostic and therapeutic purposes.
之前的一篇文章描述了几个λgt22A cDNA克隆的分离，这些克隆表达的美洲大蠊（Periplaneta americana）变应原Cr-PI可被人特应性IgE抗体和抗Cr-PI单克隆抗体识别（Wu, C. H., Lee, M. F., and Liao, S. C.(1995) J. Allergy Clin. Immunol. 96, 352 - 359）。本文呈现了编码美洲大蠊主要变应原的两个cDNA克隆的核苷酸和推导的氨基酸序列。克隆C12和C20分别编码含两个潜在N-糖基化位点的685和631个氨基酸的蛋白质。克隆C12和C20蛋白质的预测分子量分别为79,300和75,500，等电点值分别为6.26和6.63，这与美洲大蠊Cr-PI变应原测定的大小（Mr 78,000和72,000）和等电点值（6.2）相符。在两种变应原之间发现了高度的同一性（69.1%），包括几个重叠的预测中心抗原决定簇残基。基于抗融合蛋白抗体的酶联免疫吸附测定能够检测美洲大蠊粗提物、Cr-PI、重组蛋白和市售蟑螂提取物，这进一步证明了两种变应原具有共同的抗原决定簇。克隆C12和C20的重组变应原在19名对蟑螂敏感的哮喘患者中均显示出47.4%的皮肤反应性。出乎意料的是，尽管未发现与其他已知变应原的序列相似性，但发现这两种富含芳香族氨基酸的变应原与昆虫储存蛋白（20.1 - 33.9%）、昆虫保幼激素抑制蛋白（30.9 - 36.4%）和节肢动物血蓝蛋白（29.7 - 34.6%）具有显著的序列同一性。结果表明，美洲大蠊的这两种主要变应原在进化上与这些昆虫血淋巴蛋白相关，并且代表血蓝蛋白超家族中的一组新蛋白质。这些数据现在将有助于表位定位研究，并且重组变应原可能对诊断和治疗目的有价值。
