Characterization of a subfamily of beetle odorant-binding proteins found in hemolymph
Characterization of a subfamily of beetle odorant-binding proteins found in hemolymph
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DOI：
10.1074/mcp.m300018-mcp200
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发表时间：
2003-08-01
影响因子：
7
通讯作者：
Davies, PL
中科院分区：
文献类型：
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作者：
Graham, LA;Brewer, D;Davies, PL
在昆虫中，疏水性气味物质通过气味结合蛋白（OBP）通过感觉淋巴转运到感觉神经元上的受体。黄粉虫（Tenebriomolitor）是一种储粮害虫，其血淋巴中含有一组分子量为12-14-kDa的类OBP蛋白。其中一种蛋白质的结构和一种蛾信息素结合蛋白的结构已经得到解决。这两种蛋白质都有至少六个α-螺旋，内部有一个疏水的配体结合口袋，但甲虫OBP缺乏一个紧邻这个口袋的二硫键。为了探索这种差异和样本亚型多样性，T。通过尺寸排阻色谱法和反相高效液相色谱法对黄粉虫血淋巴OBP进行分级。选择的馏分进行了还原和烷基化，胰蛋白酶肽测序串联质谱法。获得了7种不同异构体的部分序列，并用于克隆9个新的cDNA编码OBP的同源性从32%到99%。更趋异的同种型具有许多疏水残基的取代，这可能改变配体结合口袋的形状和特异性。这些异构体都缺乏相同的第三个二硫键，并且彼此之间比果蝇中的38个OBP中的任何一个都更相似。它们可能是在主要昆虫目分离后通过基因复制而产生的。
In insects, hydrophobic odorants are transported through the sensillar lymph to receptors on sensory neurons by odorant-binding proteins (OBPs). The beetle Tenebrio molitor, which is a pest of stored grain products, produces a set of 12-14-kDa OBP-like proteins in its hemolymph. The structure of one of these proteins and that of a moth pheromone-binding protein have been solved. Both proteins have at least six alpha-helices with an internal, hydrophobic, ligand-binding pocket, but the beetle OBP lacks one of the disulfide bonds immediately adjacent to this pocket. To explore this difference and to sample isoform diversity, T. molitor hemolymph OBPs were fractionated by size-exclusion chromatography and reversed-phase high performance liquid chromatography. Selected fractions were reduced and alkylated, and tryptic peptides were sequenced by tandem mass spectrometry. Partial sequences of 7 different isoforms were obtained and used to clone 9 new cDNAs encoding OBPs with identities from 32 to 99%. The more divergent isoforms have numerous substitutions of hydrophobic residues that presumably alter the shape and specificity of the ligand-binding pocket. These isoforms all lack the same third disulfide bridge and are more similar to one another than to any of the 38 OBPs in Drosophila melanogaster. They have presumably arisen via gene duplication following separation of the major insect orders.