Agrobacterium tumefaciens and A. rhizogenes use different proteins to transport bacterial DNA into the plant cell nucleus.
Bottom Line: Unlike VirE2, GALLS-FL contains ATP-binding and helicase motifs similar to those in TraA, a strand transferase involved in conjugation.GALLS-FL accumulates inside the nucleus where its predicted ATP-dependent strand transferase may pull T-strands into the nucleus.These different mechanisms for nuclear import of T-strands may affect the efficiency and quality of transgenic events in plant biotechnology applications.
Affiliation: Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA. firstname.lastname@example.orgShow MeSH
Mentions: The following hypothesis summarizes the current evidence regarding the roles of VirD2 and VirE2 in nuclear import of T‐strands, and the model (Fig. 2) makes testable predictions for future research. Nuclear import of T‐strands may begin when VirD2 enters the nucleus along with ∼25 nucleotides of covalently attached ssDNA, which is sufficient to accommodate one molecule of VirE2 (Dym et al., 2008). Then VirD2 may recruit a molecule of free VirE2 (already localized inside the nucleus) to the 5′ end of the T‐strand. Protein interactions direct other DNA‐binding proteins to sites where they are needed. For example, purified RecA recombinase binds ssDNA in vitro (Radding, 1991; Kowalczykowski et al., 1994), but the RecOR complex or the RecBCD enzyme help load RecA onto ssDNA in vivo (Anderson and Kowalczykowski, 1997; Webb et al., 1997; Churchill et al., 1999; Kantake et al., 2002; Morimatsu and Kowalczykowski, 2003). Similarly, this model predicts that VirD2 will interact with VirE2 inside plant nuclei and stimulate cooperative binding of VirE2 to the 5′ end of the T‐strand in a 5′ to 3′ direction, thereby pulling T‐strands completely inside the nucleus.
Affiliation: Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA. email@example.com