Agrobacterium aiming for the host chromatin

Abstract

Agrobacterium genetically transforms its hosts by transferring a segment of DNA (T-DNA) into the host cell and integrating it into the host genome. Integration requires a close interaction between T-DNA, which is packaged into a nucleoprotein complex (T-complex) by bacterial virulence (Vir) proteins, and the host chromatin. This interaction is facilitated by the host protein VIP 1, which binds both to the major protein component of the T-complex, VirE2, and to the core histones. Recently, VIP1 has been demonstrated to mediate the interaction between plant nucleosomes and VirE2-DNA complexes (i.e., synthetic T-complex-like structures) in vitro. Here, we discuss major implications of these observations—such as the possible role of core histone modifications, proteasomal uncoating of the T-complex mediated by the bacterial F-box protein VirF, and the need for changes in chromatin structure to render it accessible to the T-DNA integration—for the process of chromatin targeting of foreign DNA and its integration into the eukaryotic genome.

Key words:

• histones
• nucleosomes
• VirE2-interacting protein 1 (VIP1)
• VirE2
• chromatin targeting
• T-complex

Figures and Tables

Figure 1. A model for the VIP1-mediated association of the Agrobacterium T-complex with the host cell chromatin. See text for details.