农杆菌T-复合物的形成与转运研究进展

在简要介绍农杆菌T-DNA转运全过程的基础上，结合作者近年的工作，重点对T-复合物的形成和T-复合物在农杆菌细胞内的转运机理的最新进展进行归纳和评述．农杆菌能够将其Ti质粒上的一段DNA以单链DNA-蛋白质复合物(简称T-复合物)的形式，通过其细胞两端的四型分泌系统(typeⅣ secretion system，T4SS)转运到宿主植物中，并使宿主发生遗传转化，因而农杆菌介导的T-DNA转运技术已成为应用最广泛的植物转基因技术，同时，由于转运T-复合物的T4SS也是某些质粒接合转移和许多病源微生物分泌致病效应蛋白的通道，因此，农杆菌T-DNA转运机理的研究受到了广泛的重视和关注，使得这方面的研究进展非常迅速．

Progress in The Formation and Transfer of Agrobacterium T-complex

Agrobacterium tumefaciens can transfer a DNA fragment (T-DNA) from its Ti plasmid to host plant and integrate the T-DNA fragment into host cell nuclear genome. Agrobacterium-mediated T-DNA transfer is the most widely used genetic transformation method for plant. The T-DNA is delivered in the form of single-stranded T-DNA-protein complex (T-complex) by the polar-located Agrobacterium type Ⅳ secretion system (T4SS) to the host cell. T4SS is ancestrally related to bacterial conjugation machines and still used by many plasmids as conjugation channel. Moreover, T4SS is also the secretion channel that used by many human bacterial pathogens to inject the effector proteins to host cells, thus contributing directly to the bacterial pathogenicity. Therefore, in addition to the technical application as a gene vector to create transgenic plants, Agrobacterium-mediated T-DNA transfer also provides a fascinating model system to study the intercellular transfer of macromolecules. The study on the molecular mechanism of T-DNA transfer arouses extensive interest and progresses rapidly in recent years. Here the recent advances in research on T-complex formation and T-complex transfer in Agrobacterium cell are reviewed.