The major birch allergen, Bet v 1, shows affinity for a broad spectrum of physiological ligands
The major birch allergen, Bet v 1, shows affinity for a broad spectrum of physiological ligands
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DOI：
10.1074/jbc.m202065200
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发表时间：
2002-06-28
影响因子：
4.8
通讯作者：
Otzen, DE
中科院分区：
文献类型：
--
作者：
Mogensen, JE;Wimmer, R;Otzen, DE
Bet v 1是一种17-kDa的蛋白质，大量存在于白色桦树的花粉中，是人类桦树花粉过敏的主要原因。它的三维结构是显着的，因为溶剂可接近的空腔穿过分子的核心。Bet v 1的生物学功能尚不清楚，尽管它与植物中的一个病程相关蛋白家族同源。在这项研究中，我们首先表明，在天然状态下的Bet v 1能够结合荧光探针8-苯胺基-1-萘磺酸（ANS）。ANS以1：1的化学计量与Betv 1结合，NMR数据表明结合发生在空腔中。使用ANS置换试验，然后，我们确定了一系列生理相关的配体，包括脂肪酸，黄酮类化合物和细胞分裂素，通常结合低微摩尔亲和力。这些配体置换ANS的能力表明它们也在空腔中结合，尽管确切的结合位点似乎在不同配体之间变化。例如，细胞分裂素似乎在靠近ANS的单独位点结合，因为它们增加了ANS.Bet v 1复合物的荧光。此外，荧光甾醇脱氢麦角甾醇结合到Bet v 1，如直接滴定所示。这项研究提供了第一个定性和定量的数据，这种重要的花粉过敏原的配体结合特性。我们的研究结果表明，配体结合是重要的生物功能的Bet v 1。
Bet v 1 is a 17-kDa protein abundantly present in the pollen of the White birch tree and is the primary cause of birch pollen allergy in humans. Its three-dimensional structure is remarkable in that a solvent-accessible cavity traverses the core of the molecule. The biological function of Bet v 1 is unknown, although it is homologous to a family of pathogenesis-related proteins in plants. In this study we first show that Bet v 1 in the native state is able to bind the fluorescent probe 8-anilino-1-naphthalenesulfonic acid (ANS). ANS binds to Bet v 1 with 1:1 stoichiometry, and NMR data indicate that binding takes place in the cavity. Using an ANS displacement assay, we then identify a range of physiologically relevant ligands, including fatty acids, flavonoids, and cytokinins, which generally bind with low micromolar affinity. The ability of these ligands to displace ANS suggests that they also bind in the cavity, although the exact binding sites seem to vary among different ligands. The cytokinins, for example, seem to bind at a separate site close to ANS, because they increase the fluorescence of the ANS.Bet v 1 complex. Also, the fluorescent sterol dehydroergosterol binds to Bet v 1 as demonstrated by direct titrations. This study provides the first qualitative and quantitative data on the ligand binding properties of this important pollen allergen. Our findings indicate that ligand binding is important for the biological function of Bet v 1.