Research Group of Host-Microbe Interactions, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway.
PLoS One. 2011;6(9):e24489. doi: 10.1371/journal.pone.0024489. Epub 2011 Sep 12.
The human polyomavirus BK (BKV) infects humans worldwide and establishes a persistent infection in the kidney. The BK virus genome encodes three regulatory proteins, large and small tumor-antigen and the agnoprotein, as well as the capsid proteins VP1 to VP3. Agnoprotein is conserved among BKV, JC virus (JCV) and SV40, and agnoprotein-deficient mutants reveal reduced viral propagation. Studies with JCV and SV40 indicate that their agnoproteins may be involved in transcription, replication and/or nuclear and cellular release of the virus. However, the exact function(s) of agnoprotein of BK virus remains elusive.
As a strategy of exploring the functions of BKV agnoprotein, we decided to look for cellular interaction partners for the viral protein. Several partners were identified by yeast two-hybrid assay, among them α-SNAP which is involved in disassembly of vesicles during secretion. BKV agnoprotein and α-SNAP were found to partially co-localize in cells, and a complex consisting of agnoprotein and α-SNAP could be co-immunoprecipitated from cells ectopically expressing the proteins as well as from BKV-transfected cells. The N-terminal part of the agnoprotein was sufficient for the interaction with α-SNAP. Finally, we could show that BKV agnoprotein negatively interferes with secretion of VSVG-EGFP reporter suggesting that agnoprotein may modulate exocytosis.
We have identified the first cellular interaction partner for BKV agnoprotein. The most N-terminal part of BKV agnoprotein is involved in the interaction with α-SNAP. Presence of BKV agnoprotein negatively interferes with secretion of VSVG-EGFP reporter.
人类多瘤病毒 BK（BKV）在全球范围内感染人类，并在肾脏中建立持续性感染。BKV 基因组编码三种调节蛋白，即大、小肿瘤抗原和 agnoprotein，以及衣壳蛋白 VP1 至 VP3。Agnoprotein 在 BKV、JC 病毒（JCV）和 SV40 中保守存在，并且 agnoprotein 缺失突变体显示出病毒增殖减少。对 JCV 和 SV40 的研究表明，它们的 agnoproteins 可能参与病毒的转录、复制和/或核内和细胞内释放。然而，BK 病毒 agnoprotein 的确切功能仍不清楚。
作为探索 BKV agnoprotein 功能的策略，我们决定寻找病毒蛋白的细胞相互作用伙伴。酵母双杂交实验鉴定了几个相互作用伙伴，其中包括参与分泌过程中囊泡解体的α-SNAP。发现 BKV agnoprotein 和 α-SNAP 在细胞中部分共定位，并且可以从异位表达这些蛋白的细胞以及转染 BKV 的细胞中共同免疫沉淀包含 agnoprotein 和 α-SNAP 的复合物。Agnoprotein 的 N 端部分足以与 α-SNAP 相互作用。最后，我们可以证明 BKV agnoprotein 可负性干扰 VSVG-EGFP 报告子的分泌，表明 agnoprotein 可能调节胞吐作用。
我们已经鉴定出 BKV agnoprotein 的第一个细胞相互作用伙伴。BKV agnoprotein 的最 N 端部分参与与 α-SNAP 的相互作用。BKV agnoprotein 的存在可负性干扰 VSVG-EGFP 报告子的分泌。
