T-DNA border sequences required for crown gall tumorigenesis.
T-DNA border sequences required for crown gall tumorigenesis.
复制标题
冠瘿肿瘤发生所需的 T-DNA 边界序列。
DOI：
10.1073/pnas.82.15.5112
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发表时间：
1985
影响因子：
11.1
通讯作者：
Ream,LW
中科院分区：
文献类型：
--
作者：
Peralta,EG;Ream,LW
在肿瘤诱导质粒pTiA 6 NC中，在两个相邻但不连续的T-DNA，TL和TR（左和右T-DNA）的末端存在类似的23个碱基对（bp）的正向重复。因此，三个边界重复序列位于TL的右边，一个位于TL的左边，TL携带肿瘤维持所需的基因。为了确定T-DNA转移和整合（随后称为T-DNA传输）是否需要除了23 bp边界重复序列之外的序列，我们构建了一个删除三个潜在的TL右边界（TL右边界和两个TR边界）的缺失。由于这种缺失严重削弱了毒力，我们重新引入限制性片段含有TL右边界重复在一个新的位置TL和测试他们的能力，恢复毒力。携带边缘重复序列的片段，其侧翼为左侧至少67 bp的野生型Ti质粒序列和右侧1035 bp的野生型Ti质粒序列，完全恢复了毒力。较小的片段恢复毒力显着，但不完全，即使边界重复保持完整。因此，在完全活性片段中的边界重复侧翼的T区序列刺激T-DNA整合。当以野生型方向插入时完全恢复毒力的片段在相反方向仅轻微刺激毒力。因此，右边界序列在一个方向上最好地促进T-DNA转移和整合。
Similar 23-base-pair (bp) direct repeats occur at the ends of two adjacent but noncontiguous T-DNAs, TL and TR (left and right T-DNA), in the tumor-inducing plasmid pTiA6NC. Thus, three border repeats lie right and one lies left of TL, which carries the genes needed for tumor maintenance. To determine whether T-DNA transfer and integration (subsequently called T-DNA transmission) require sequences in addition to the 23-bp border repeat, we constructed a deletion removing the three potential TL right borders (the TL right border and both TR borders). Since this deletion severely attenuated virulence, we reintroduced restriction fragments containing the TL right border repeat at a new location to the right of TL and tested their ability to restore virulence. Fragments that carried the border repeat flanked by at least 67 bp of wild-type Ti plasmid sequences on the left and 1035 bp on the right restored virulence completely. Smaller fragments restored virulence significantly but not fully, even though the border repeat remained intact. Therefore, T-region sequences flanking the border repeat in the fully active fragments stimulated T-DNA integration. Fragments that restored virulence fully when inserted in the wild-type orientation stimulated virulence only slightly in the opposite orientation. Thus, the right border sequence promotes T-DNA transfer and integration best in one direction.