Plant Science Division, Research School of Biology, College of Medicine, Biology and Environment, The Australian National University, Canberra, Australia.
Plant Signal Behav. 2010 Oct;5(10):1272-5. doi: 10.4161/psb.5.10.13013. Epub 2010 Oct 1.
Effectors are pathogen-encoded proteins that are thought to facilitate infection by manipulation of host cells. Evidence showing that the effectors of some eukaryotic plant pathogens are able to interact directly with cytoplasmic host proteins indicates that translocation of these proteins into host cells is an important part of infection. Recently, we showed that the flax rust effectors AvrM and AvrL567 are able to internalize into plant cells in the absence of the pathogen. Further, N-terminal sequences that were sufficient for uptake were identified for both these proteins. In light of the possibility that the internalization of fungal and oomycete effectors may require binding to specific phospholipids, the lipid binding activities of AvrM and AvrL567 mutants with different abilities to enter cells were tested. While AvrL567 was not found to bind to phospholipids, AvrM bound strongly to phosphatidyl inositol, phosphatidyl inositol monophosphates and phosphatidyl serine. However, a fragment of AvrM sufficient to direct uptake of a fusion protein into plant cells did not bind to these phospholipids. Thus, our results do not support the role of specific binding of AvrM and AvrL567 to phospholipids for uptake into the plant cytoplasm.
效应子是病原体编码的蛋白质，被认为通过操纵宿主细胞来促进感染。有证据表明，一些真核植物病原体的效应子能够直接与细胞质宿主蛋白相互作用，这表明这些蛋白向宿主细胞的易位是感染的重要组成部分。最近，我们表明亚麻锈病效应子 AvrM 和 AvrL567 能够在没有病原体的情况下内化到植物细胞中。此外，确定了这两种蛋白内化所需的足够的 N 端序列。鉴于真菌和卵菌效应子的内化可能需要与特定磷脂结合的可能性，测试了具有不同进入细胞能力的 AvrM 和 AvrL567 突变体的脂质结合活性。虽然没有发现 AvrL567 结合磷脂，但 AvrM 强烈结合磷脂酰肌醇、磷脂酰肌醇单磷酸和磷脂酰丝氨酸。然而，足以将融合蛋白引导进入植物细胞内化的 AvrM 片段不与这些磷脂结合。因此，我们的结果不支持 AvrM 和 AvrL567 与磷脂特异性结合以摄取到植物细胞质中的作用。
