德国杜伊斯堡-埃森大学(University Duisburg-Essen)教授Peter Bayer和Anja Matena和他们来自苏格兰的同事们如今识破了卵菌(oomycete)感染它们宿主的策略。相关研究结果发表在美国著名期刊PNAS上。
卵菌中很多物种是寄生菌，这些看似无害的微动物(animalcule)能够导致巨大的经济损失，比如致病疫霉(Phytophthora infestans)就是其中的一个代表。致病疫霉是一种导致马铃薯疫病的致病性卵菌，而且在1845年，它导致爱尔兰发生大饥荒。直到现在，这种有机体仍然给全世界种植业带来相当于上百万美元的农作物损失。然而，卵菌能够攻击和感染的对象不仅是植物，而且也包括动物以及在少数情况下还包括人类。因此，卵菌和它们的传播方式激起科学家的浓厚兴趣。
来自“结构与医学生化”研究小组的科学家与来自苏格兰阿伯丁大学和邓迪大学的同事们进行合作研究，并破解了卵菌刺入它们的宿主细胞的机制。就像特洛伊木马一样，它们让一种蛋白潜入宿主细胞来减弱宿主的免疫系统功能，从而为这种寄生菌侵入扫清道路。这也是科学家第一次能够证实宿主细胞表面蛋白上存在的化学修饰性氨基酸(sulpho-tyrosine，即磺基酪氨酸)作为该寄生菌停靠和入侵的分子锚(molecular anchor)。
这一发现确实是一项影响深远的发现，因为这些磺基酪氨酸也在HIV病毒和疟原虫(plasmodium)---两者分别是爱滋病(AIDS)和疟疾的致病因子---感染它们的人类宿主过程当中发挥着关键性作用。如今，科学家相信他们已经破解了不同寄生生物感染真核生物宿主时所采用的一种普遍适用的机制。(生物谷：towersimper编译)
doi:10.1073/pnas.1113775109
PMC:
PMID:
Host-targeting protein 1 (SpHtp1) from the oomycete Saprolegnia parasitica translocates specifically into fish cells in a tyrosine-O-sulphate–dependent manner
Stephan Wawra, Judith Bain, Elaine Durward, Irene de Bruijn, Kirsty L. Minor, Anja Matena, Lars Löbach, Stephen C. Whisson, Peter Bayer, Andrew J. Porter, Paul R. J. Birch, Chris J. Secombes, and Pieter van West
The eukaryotic oomycetes, or water molds, contain several species that are devastating pathogens of plants and animals. During infection, oomycetes translocate effector proteins into host cells, where they interfere with host-defense responses. For several oomycete effectors (i.e., the RxLR-effectors) it has been shown that their N-terminal polypeptides are important for the delivery into the host. Here we demonstrate that the putative RxLR-like effector, host-targeting protein 1 (SpHtp1), from the fish pathogen Saprolegnia parasitica translocates specifically inside host cells. We further demonstrate that cell-surface binding and uptake of this effector protein is mediated by an interaction with tyrosine-O-sulfate–modified cell-surface molecules and not via phospholipids, as has been reported for RxLR-effectors from plant pathogenic oomycetes. These results reveal an effector translocation route based on tyrosine-O-sulfate binding, which could be highly relevant for a wide range of host–microbe interactions.
