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Publication Abstract from PubMed

Agrobacterium is known for gene transfer to plants. In addition to a linear ssDNA oligonucleotide, Agrobacterium tumefaciens secretes an abundant ssDNA-binding effector, VirE2. In many ways VirE2 adapts the conjugation mechanism to transform the eukaryotic host. The crystal structure of VirE2 shows two compact domains joined by a flexible linker. Bound to ssDNA, VirE2 forms an ordered solenoidal shell, or capsid known as the T-complex. Here, we present a three-dimensional reconstruction of the VirE2-ssDNA complex using cryo-electron microscopy and iterative helical real-space reconstruction. High-resolution refinement was not possible due to inherent heterogeneity in the protein structure. By a combination of computational modeling, chemical modifications, mass spectroscopy, and electron paramagnetic resonance, we found that the N-terminal domain is tightly constrained by both tangential and longitudinal links, while the C terminus is weakly constrained. The quaternary structure is thus rigidly assembled while remaining locally flexible. This flexibility may be important in accommodating substrates without sequence specificity.

Variable Internal Flexibility Characterizes the Helical Capsid Formed by Agrobacterium VirE2 Protein on Single-Stranded DNA.,Bharat TA, Zbaida D, Eisenstein M, Frankenstein Z, Mehlman T, Weiner L, Sorzano CO, Barak Y, Albeck S, Briggs JA, Wolf SG, Elbaum M Structure. 2013 Jun 11. pii: S0969-2126(13)00157-3. doi:, 10.1016/j.str.2013.04.027. PMID:23769668^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.