GALLS, A Novel Agrobacterium Rhizogenes Protein Required for Gene Transfer to Plants

根癌农杆菌（Agrobacterium tumefaciens）和A.根瘤菌通过IV型分泌系统将基因和蛋白质转移到植物细胞中。转移DNA（T-DNA）在植物细胞中稳定遗传和表达，引起冠瘿病或毛状根病。VirE2是一种分泌的ssDNA结合蛋白，对有效的T-DNA转移和整合至关重要。VirE2靶向T-DNA进入细胞核。尽管VirE 2在植物基因转移中具有重要作用，但一些A.根瘤菌缺乏VirE2，但它们仍然有效地转移T-DNA。一个来自A. rhizogenes恢复对virE2-A的致病性。根瘤菌GALLS，如VirE2，可以分泌到植物细胞中。GALLS含有一个假定的核定位信号和解旋酶基序类似的TraA，介导的共轭DNA转移。GALLS包含三个重复序列，不像任何已知的蛋白质。GALLS替代了VirE2，但并不像它。GALLS是否执行类似的生化功能，或者它是否通过提供新的活性来补偿VirE2的损失？为了解决这个问题，将进行以下工作：在GALLS中创建突变，以识别对DNA转移重要的结构域。在植物中表达GALLS，以询问它是否在植物细胞中起作用并在细胞核中积累。询问GALLS是否保护植物细胞或细菌中的T-DNA。测试GALLS的解旋酶活性和与ATP或DNA的结合。冠瘿是重要的经济作物，A.根癌农杆菌IV型分泌是人类病原体中相关系统的极好模型。植物转化A.根癌农杆菌被广泛用于创造转基因作物。GALLS介导基因转移到植物中的重要步骤，并可能提供进入细胞核的替代途径。这可以允许更好地控制转基因结构、拷贝数和位置。因此，了解GALLS是如何工作的非常重要。

Agrobacterium tumefaciens and A. rhizogenes transfer genes and proteins into plant cells via a type IV secretion system. Transferred DNA (T-DNA) is stably inherited and expressed in plant cells, causing crown gall or hairy root disease. VirE2 is a secreted ssDNA-binding protein crucial for efficient T-DNA transfer and integration. VirE2 targets T-DNA into the nucleus. Despite the importance of VirE2 for gene transfer to plants, some strains of A. rhizogenes lack VirE2, but they still transfer T-DNA efficiently. A gene (GALLS) from A. rhizogenes restores pathogenicity to virE2 - A. tumefaciens. GALLS, like VirE2, may be secreted into plant cells. GALLS contains a putative nuclear localization signal and helicase motifs similar to those in TraA, which mediates conjugal DNA transfer. GALLS contains three repeats that do not resemble any known protein. GALLS substitutes for VirE2 but does not resemble it. Does GALLS perform similar biochemical functions, or does it compensate for loss of VirE2 by providing a new activity? To address this, the following will be done: Create mutations in GALLS to identify domains important for DNA transfer. Express GALLS in plants to ask whether it functions in plant cells and accumulates in the nucleus. Ask whether GALLS protects T- DNA in plant cells or bacteria. Test GALLS for helicase activity and binding to ATP or DNA. Crown gall is economically important, and A. tumefaciens type IV secretion is an excellent model for related systems in human pathogens. Plant transformation by A. tumefaciens is widely used to create transgenic crops. GALLS mediates essential steps in gene transfer to plants and may provide an alternate route into the nucleus. This may allow better control over transgene structure, copy number, and location. Thus, it is important to understand how GALLS works.