Absence of plasmids encoding adhesion-related proteins in non-insect-transmissible strains of Spiroplasma citri
Absence of plasmids encoding adhesion-related proteins in non-insect-transmissible strains of Spiroplasma citri
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DOI：
10.1099/mic.0.28541-0
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发表时间：
2006-03-01
期刊：
影响因子：
2.8
通讯作者：
Renaudin, J
中科院分区：
文献类型：
--
作者：
Berho, N;Duret, S;Renaudin, J
在植物病原性软体柑橘螺原体中，螺旋蛋白是细胞表面的主要脂蛋白，被认为是参与螺原体与其昆虫载体相互作用的成分之一。为了鉴定螺旋蛋白以外的表面蛋白，通过使用螺旋蛋白缺陷型 S. citri 突变体 GII3-9a2 对小鼠进行免疫接种来产生单克隆抗体 (mAb)。发现 mAb 10G3 与多种 43-47 和 80-95 kDa 的多肽发生反应，所有这些多肽均在 Triton X-114 分配蛋白质后在去污剂相中检测到。对 GII3-9a2 的两个主要多肽 P47 和 P80 与 mAb 10G3 反应进行的质谱 (MALDI-TOF) 分析表明，P47 是加工产物，代表 P80 的 C 末端部分。序列同源性搜索表明，P80 与 S. citri BR3 的 S. citri 粘附相关蛋白 P89 (Sarp1) 具有很强的相似性，并且是 S. citri GII-3 基因组编码的 8 个 Scarp 之一（命名为 Scarp4a）。八个scarp 基因由质粒pSci1-5 携带。使用 mAb 10G3 对蛋白质进行蛋白质免疫印迹显示，与昆虫传播的柑橘沙门氏菌菌株 GII-3 相比，非昆虫传播的菌株 ASP-1、R8A2 和 44 不表达 Scarps。 Southern blot杂交实验表明，这些菌株不具有scarp基因，并且不携带质粒pSci1-5。然而，缺乏 pSci5 的柑橘链霉菌 GII3-5 仍能有效传播，这表明在柑橘链霉菌 GII-3 的遗传背景中，pSci5 编码的基因，特别是斯卡普2b、3b 和 5a，对于昆虫传播并不是必需的。质粒编码基因是否参与柑橘链霉菌通过其叶蝉载体的传播仍有待确定。
In the plant-pathogenic mollicute Spiroplasma citri, spiralin is the major lipoprotein at the cell surface and is thought to be one of the components involved in the interactions of the spiroplasma with its insect vector. With the aim of identifying surface proteins other than spiralin, monoclonal antibodies (mAbs) were produced by immunization of mice with the spiralin-defective S. citri mutant GII3-9a2. mAb 10G3 was found to react with several polypeptides of 43-47 and 80-95 kDa, all of which were detected in the detergent phase after Triton X-114 partitioning of proteins. Mass spectrometry (MALDI-TOF) analyses of the two major polypeptides P47 and P80 of GII3-9a2, reacting with mAb 10G3, revealed that P47 was a processed product and represented the C-terminal moiety of P80. Search for sequence homologies revealed that P80 shared strong similarities with the S. citri adhesion-related protein P89 (Sarp1) of S. citri BR3, and is one (named Scarp4a) of the eight Scarps encoded by the S. citri GII-3 genome. The eight scarp genes are carried by plasmids pSci1-5. Western immunoblotting of proteins with mAb 10G3 revealed that, in contrast to the insect-transmissible S. citri strain GII-3, the non-insect-transmissible strains ASP-1, R8A2 and 44 did not express Scarps. Southern blot hybridization experiments indicated that these strains possessed no scarp genes, and did not carry plasmids pSci1-5. However, S. citri strain GII3-5, lacking pSci5, was still efficiently transmitted, showing that, in the genetic background of S. citri GII-3, the pSci5-encoded genes, and in particular scarp2b, 3b and 5a, are not essential for insect transmission. Whether plasmid-encoded genes are involved in transmission of S. citri by its leafhopper vector remains to be determined.