A Distinct, Non-Virion Plant Virus Movement Protein Encoded by a Crinivirus Essential for Systemic Infection.
A Distinct, Non-Virion Plant Virus Movement Protein Encoded by a Crinivirus Essential for Systemic Infection.
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DOI：
10.1128/mbio.02230-18
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发表时间：
2018-11-20
期刊：
影响因子：
6.4
通讯作者：
Falk BW
中科院分区：
文献类型：
--
作者：
Qiao W;Medina V;Kuo YW;Falk BW
植物病毒编码特定的蛋白质，促进其在宿主植物中建立多细胞/系统感染的能力。相对较少的是知道的运输机制的植物病毒的感染是韧皮部有限的，包括那些家庭的梭状病毒。这些病毒具有复杂的、长的丝状病毒体，通过韧皮部传播。鸡传染性黄化病毒（LIYV）编码一种非病毒体蛋白P26，其在胞间连丝陷窝区域上形成质膜沉积物，并且LIYV病毒体一直被发现附着于这些沉积物。在这里，我们表明，P26是一个独特的运动蛋白所需的LIYV系统感染植物。LIYV P26与其他蛋白质没有序列相似性，但其他海百合病毒编码P26直系同源物。然而，这些未能补充LIYV P26突变体的运动。植物感染病毒利用涉及多种病毒和宿主因子的各种策略来实现其相容宿主的成功系统感染。马铃薯传染性黄化病毒（LIYV）是梭状病毒科（Closteroviridae）百合病毒属（Crinivirus）的一种病毒，具有长的丝状曲折病毒粒子，在植物宿主中引起韧皮部限制性感染。LIYV编码的P26是一种独特的非病毒体蛋白，与当前数据库中的蛋白质没有相似之处：它诱导质膜沉积在胞间连丝（PD）凹坑区域，并推测在受感染植物内的LIYV病毒体运输中发挥作用。本研究证明P26是一种PD定位蛋白，并通过突变分析在植物中检测其生物学意义。LIYV P26基因敲除突变体（P26 X）在本氏烟（Nicotiana benthamiana）的接种叶片中表现出病毒RNA复制和病毒粒子形成，但不能引起系统感染。通过使用修饰的绿色荧光蛋白（GFP）标记的LIYV P26 X的确认显示GFP仅在浸润的叶组织中积累，而野生型LIYV GFP容易在韧皮部中系统地传播。通过反式互补来拯救P26 X的尝试是阴性的。然而，LIYV基因组中易位的LIYV P26基因拯救了全身感染，但来自其他海百合病毒的P26直系同源物没有。植物突变试验表明，P26的缺失以及11个特异性丙氨酸扫描突变体中的2个，消除了系统感染N.本萨米亚纳
Plant viruses encode specific proteins that facilitate their ability to establish multicellular/systemic infections in their host plants. Relatively little is known of the transport mechanisms for plant viruses whose infections are phloem limited, including those of the family Closteroviridae. These viruses have complex, long filamentous virions that spread through the phloem. Lettuce infectious yellows virus (LIYV) encodes a non-virion protein, P26, which forms plasmalemma deposits over plasmodesmata pit fields, and LIYV virions are consistently found attached to those deposits. Here we demonstrate that P26 is a unique movement protein required for LIYV systemic infection in plants. LIYV P26 shows no sequence similarities to other proteins, but other criniviruses encode P26 orthologs. However, these failed to complement movement of LIYV P26 mutants. Plant-infecting viruses utilize various strategies involving multiple viral and host factors to achieve successful systemic infections of their compatible hosts. Lettuce infectious yellows virus (LIYV), genus Crinivirus, family Closteroviridae, has long, filamentous flexuous virions and causes phloem-limited infections in its plant hosts. The LIYV-encoded P26 is a distinct non-virion protein that shows no similarities to proteins in current databases: it induces plasmalemma deposits over plasmadesmata (PD) pit fields and is speculated to have roles in LIYV virion transport within infected plants. In this study, P26 was demonstrated to be a PD-localized protein, and its biological significance was tested in planta by mutagenesis analysis. An LIYV P26 knockout mutant (P26X) showed viral RNA replication and virion formation in inoculated leaves of Nicotiana benthamiana plants, but failed to give systemic infection. Confirmation by using a modified green fluorescent protein (GFP)-tagged LIYV P26X showed GFP accumulation only in infiltrated leaf tissues, while wild-type LIYV GFP readily spread systemically in the phloem. Attempts to rescue P26X by complementation in trans were negative. However a translocated LIYV P26 gene in the LIYV genome rescued systemic infection, but P26 orthologs from other criniviruses did not. Mutagenesis in planta assays showed that deletions in P26, as well as 2 of 11 specific alanine-scanning mutants, abolished the ability to systemically infect N. benthamiana.