Stączek Sylwia, Zdybicka-Barabas Agnieszka, Mak Paweł, Sowa-Jasiłek Aneta, Kedracka-Krok Sylwia, Jankowska Urszula, Suder Piotr, Wydrych Jerzy, Grygorczuk Katarzyna, Jakubowicz Teresa, Cytryńska Małgorzata
Department of Immunobiology, Institute of Biology and Biochemistry, Faculty of Biology and Biotechnology, Maria Curie-Skłodowska University, Akademicka 19 St., 20-033 Lublin, Poland.
Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Gronostajowa 7 St., 30-387 Krakow, Poland; Malopolska Centre of Biotechnology, Gronostajowa 7A St., 30-387 Krakow, Poland.
J Insect Physiol. 2018 Feb-Mar;105:18-27. doi: 10.1016/j.jinsphys.2017.12.009. Epub 2017 Dec 28.
A lipid-binding protein apolipophorin III (apoLp-III), an exchangeable component of lipophorin particles, is involved in lipid transport and immune response in insects. In Galleria mellonella, apoLp-III binding to high-density lipophorins and formation of low-density lipophorin complexes upon immune challenge was reported. However, an unanswered question remains whether apoLp-III could form different complexes in a pathogen-dependent manner. Here we report on pathogen- and time-dependent alterations in the level of apoLp-III free and lipophorin-bound form that occur in the hemolymph and hemocytes shortly after immunization of G. mellonella larvae with different pathogens, i.e. Gram-negative bacterium Escherichia coli, Gram-positive bacterium Micrococcus luteus, yeast-like fungus Candida albicans, and filamentous fungus Fusarium oxysporum. These changes were accompanied by differently persistent re-localization of apoLp-III in the hemocytes. The apoLp-III-interacting proteins were recovered from immune hemolymph by affinity chromatography on a Sepharose bed with immobilized anti-apoLp-III antibodies. ApoLp-I, apoLp-II, hexamerin, and arylphorin were identified as main components that bound to apoLp-III; the N-terminal amino acid sequences of G. mellonella apoLp-I and apoLp-II were determined for the first time. In the recovered complexes, the pathogen-dependent differences in the content of individual apolipophorins were detected. Apolipophorins may thus be postulated as signaling molecules responding in an immunogen-dependent manner in early steps of G. mellonella immune response.
脂质结合蛋白载脂蛋白III（apoLp-III）是脂蛋白颗粒的一种可交换成分，参与昆虫的脂质运输和免疫反应。在大蜡螟中，已有报道称apoLp-III与高密度脂蛋白结合，并在免疫刺激后形成低密度脂蛋白复合物。然而，apoLp-III是否能以病原体依赖的方式形成不同的复合物这一问题仍未得到解答。在此，我们报告了在用不同病原体，即革兰氏阴性菌大肠杆菌、革兰氏阳性菌藤黄微球菌、酵母样真菌白色念珠菌和丝状真菌尖孢镰刀菌免疫大蜡螟幼虫后不久，血淋巴和血细胞中游离形式和与脂蛋白结合形式的apoLp-III水平在病原体和时间依赖性方面的变化。这些变化伴随着apoLp-III在血细胞中不同程度的持续性重新定位。通过在固定有抗apoLp-III抗体的琼脂糖柱上进行亲和层析，从免疫血淋巴中回收了与apoLp-III相互作用的蛋白质。已鉴定出apoLp-I、apoLp-II、六聚蛋白和芳基脂蛋白是与apoLp-III结合的主要成分；首次测定了大蜡螟apoLp-I和apoLp-II的N端氨基酸序列。在回收的复合物中，检测到了单个载脂蛋白含量的病原体依赖性差异。因此，可以推测载脂蛋白在大蜡螟免疫反应的早期阶段作为信号分子以免疫原依赖的方式做出反应。
