The role of the human guanylate-binding protein 1 in the formation and trafficking of phagosomes and other pathogen containing membrane compartments

鸟苷酸结合蛋白（gbp）属于大gtp酶的动力蛋白超家族，参与各种细胞膜重塑事件。GBPs与动力蛋白样Mx蛋白以及p47免疫相关GTPase （IRGs）具有相同的生化和功能特性，如干扰素的强诱导、抗致病活性、膜结合、弱核苷酸结合以及组装刺激的内在GTPase活性增加。在细胞中，内源性人GBP1在被氟化铝激活后显示出囊泡染色模式并重新定位到高尔基体复合体。这一过程需要对hGBP1的c端进行翻译后脂质修饰，hGBP1是一种未知的干扰素诱导因子，并且通过氟化铝结合活性位点诱导构象改变。最近，我们已经能够在体外用重组脂质修饰的hGBP1再现这种膜募集，重组脂质修饰的hGBP1是由共表达系统和体外修饰反应相结合产生的。此外，我们在新形成的吞噬体中发现细胞hGBP1独立于其激活状态和其他干扰素刺激因子。因此，我们想要确定负责这种招募的吞噬体因子，以及hGBP1对吞噬体和其他含病原体的膜室的成熟和运输的影响。

Guanylate-binding proteins (GBPs) belong to the dynamin superfamily of large GTPases which are involved in various cellular membrane remodelling events. GBPs share biochemical and functional properties with the dynamin-like Mx proteins as well as the p47 immunity-related GTPases (IRGs), such as a strong induction by interferons, anti-pathogenic activity, membrane association, weak nucleotide binding and an assembly-stimulated increase of the intrinsic GTPase activity. In cells, endogenous human GBP1 shows a vesicular staining pattern and relocalises to the Golgi complex upon activation by aluminium fluoride. This process requires posttranslational lipid modification of the C-terminus of hGBP1, an unknown interferon inducible factor and a conformation change which is induced by binding of aluminium fluoride to the active site. Recently, we have been able to recapitulate this membrane recruitment in vitro with recombinant lipid-modified hGBP1 produced by a combination of co-expression systems and in vitro modification reactions. Moreover, we found cellular hGBP1 at newly forming phagosomes independently of its activation state and of other interferon-stimulated factors. Therefore, we want identify the phagosomal factors responsible for this recruitment and also the impact of hGBP1 on the maturation and trafficking of phagosomes and other pathogen-containing membrane compartments.