Two chorismate mutase genes from the root-knot nematode Meloidogyne incognita
Two chorismate mutase genes from the root-knot nematode Meloidogyne incognita
复制标题
DOI：
10.1111/j.1364-3703.2004.00257.x
复制
发表时间：
2005-01-01
影响因子：
4.9
通讯作者：
Hussey, RS
中科院分区：
文献类型：
--
作者：
Huang, GZ;Dong, RH;Hussey, RS
植物寄生线虫食管腺中表达的编码分泌蛋白的寄生基因在线虫入侵寄主植物、建立取食位点和抑制寄主防御方面发挥着关键作用。从南方根结线虫食管腺细胞消减 cDNA 文库中鉴定出两个可能在这些过程中的一个或多个过程中发挥作用的分支酸变位酶 (CM) 基因。这些带有氨基末端信号肽的南方根结线虫酶（称为 MI-CM-1 和 MI-CM-2）与爪哇根结线虫和细菌中的分支酸变位酶显着相似。通过表达 Mi-cm-1 或 Mi-cm-2 来补充大肠杆菌 CM 缺陷突变体，证实了它们的 CM 活性。原位mRNA杂交显示Mi-cm-1和Mi-cm-2的转录本在南方根结线虫的两个腹下食管腺细胞中特异性积累。 RT-PCR 分析证实，它们的转录本丰度在线虫早期寄生幼虫阶段较高，而在线虫后期寄生阶段较低（Mi-cm-1）或检测不到（Mi-cm-2）。 Southern 印迹分析表明这些 CM 基因是根结线虫属中一个小型多基因家族的成员。 CM 在专门的静坐内寄生线虫物种中广泛存在，表明这种多功能酶可能是调节植物寄生的关键因素。
Parasitism genes encoding secretory proteins expressed in the oesophageal glands of phytoparasitic nematodes play critical roles in nematode invasion of host plants, establishment of feeding sites and suppression of host defences. Two chorismate mutase (CM) genes potentially having a role in one or more of these processes were identified from a Meloidogyne incognita oesophageal gland-cell subtractive cDNA library. These M. incognita enzymes (designated as MI-CM-1 and MI-CM-2) with amino-terminal signal peptides, were significantly similar to chorismate mutases in M.javanica and bacteria. The complementation of an Escherichia coli CM-deficient mutant by the expression of Mi-cm-1 or Mi-cm-2 confirmed their CM activity. In-situ mRNA hybridization showed that the transcripts of Mi-cm-1 and Mi-cm-2 accumulated specifically in the two subventral oesophageal gland cells of M. incognita. RT-PCR analysis confirmed that their transcript abundances were high in the early parasitic juvenile stages, and low (Mi-cm-1) or undetectable (Mi-cm-2) in later parasitic stages of the nematode. Southern blot analysis revealed that these CM genes were members of a small multigene family in Meloidogyne species. The widespread presence of CMs in the specialized sedentary endoparasitic nematode species suggests that this multifunctional enzyme may be a key factor in modulating plant parasitism.