THE OMEGA-SEQUENCE OF VIRD2 IS IMPORTANT BUT NOT ESSENTIAL FOR EFFICIENT TRANSFER OF T-DNA BY AGROBACTERIUM-TUMEFACIENS

The VirD2 protein of Agrobacterium tumefaciens contains defined sequen ces necessary for processing and transferring the T-DNA during transfo rmation of plant cells. We performed a mutational analysis of the cons erved omega sequence of VirD2, whose role has proven to be difficult t o elucidate so far, In this report, we show that a deletion of these 5 amino acids or their replacement by 5 glycines reduced T-DNA transfer considerably, compared with wild type, demonstrating that the omega s equence is important for the efficient transfer of T-DNAs. However, th e efficiency and pattern of integration of the T-DNAs were not affecte d by any modifications of the omega sequence. The importance of the C terminus of VirD2 for T-DNA transfer is discussed.