Pakkanen Kirsi, Karttunen Jenni, Virtanen Salla, Vuento Matti
Department of Biological and Environmental Science, University of Jyväskylä, Finland.
Virus Res. 2008 Mar;132(1-2):187-91. doi: 10.1016/j.virusres.2007.10.008. Epub 2007 Nov 28.
One of the essential steps in canine parvovirus (CPV) infection, the release from endosomal vesicles, is dominated by interactions between the virus capsid and the endosomal membranes. In this study, the effect of sphingomyelin and phosphatidyl serine on canine parvovirus capsid and on the phospholipase A(2) (PLA(2)) activity of CPV VP1 unique N-terminus was analyzed. Accordingly, a significant (P< or =0.05) shift of tryptophan fluorescence emission peak was detected at pH 5.5 in the presence of sphingomyelin, whereas at pH 7.4 a similar but minor shift was observed. This effect may relate to the exposure of VP1 N-terminus in acidic pH as well as to interactions between sphingomyelin and CPV. When the phenomenon was further characterized using circular dichroism spectroscopy, differences in CPV capsid CD spectra with and without sphingomyelin and phosphatidyl serine were detected, corresponding to data obtained with tryptophan fluorescence. However, when the enzymatic activity of CPV PLA(2) was tested in the presence of sphingomyelin, no significant effect in the function of the enzyme was detected. Thus, the structural changes observed with spectroscopic techniques appear not to manipulate the activity of CPV PLA(2), and may therefore implicate alternative interactions between CPV capsid and sphingomyelin.
犬细小病毒（CPV）感染的关键步骤之一，即从内体囊泡中释放，主要由病毒衣壳与内体膜之间的相互作用主导。在本研究中，分析了鞘磷脂和磷脂酰丝氨酸对犬细小病毒衣壳以及对CPV VP1独特N端磷脂酶A2（PLA2）活性的影响。相应地，在鞘磷脂存在的情况下，于pH 5.5检测到色氨酸荧光发射峰有显著（P≤0.05）位移，而在pH 7.4观察到类似但较小的位移。这种效应可能与VP1 N端在酸性pH下的暴露以及鞘磷脂与CPV之间的相互作用有关。当使用圆二色光谱进一步表征该现象时，检测到有鞘磷脂和无鞘磷脂及磷脂酰丝氨酸时CPV衣壳CD光谱的差异，这与色氨酸荧光获得的数据一致。然而，当在鞘磷脂存在的情况下测试CPV PLA2的酶活性时，未检测到该酶功能有显著影响。因此，用光谱技术观察到的结构变化似乎并未操纵CPV PLA2的活性，因此可能意味着CPV衣壳与鞘磷脂之间存在其他相互作用。
