JB Accepts, published online ahead of print on 29 September 2006

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J. Bacteriol. doi:10.1128/JB.00747-06
Copyright (c) 2006, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved.

Agrobacterium rhizogenes GALLS Protein Contains Domains for ATP Binding, Nuclear Localization, and Type IV Secretion

Larry D. Hodges, Annette C. Vergunst, Jason Neal-McKinney, Amke den Dulk-Ras, Deborah M. Moyer, Paul J. J. Hooykaas, and Walt Ream^*

Department of Microbiology, Oregon State University, Corvallis, OR 97331, USA, and Institute of Biology, Leiden University, Clusius Laboratory, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands

^* To whom correspondence should be addressed. Email: reamw{at}orst.edu.

Agrobacterium tumefaciens and A. rhizogenes are closely related plant pathogens that cause different diseases, crown gall and hairy root. Both diseases result from transfer, integration, and expression of plasmid-encoded bacterial genes located on the transferred DNA (T-DNA) in the plant genome. Bacterial virulence (Vir) proteins necessary for infection are also translocated into plant cells. Transfer of single-stranded DNA (ssDNA) and Vir proteins requires a type IV secretion system (T4SS), a protein complex spanning the bacterial envelope. A. tumefaciens translocates the ssDNA-binding protein VirE2 into plant cells where it binds single-stranded T-DNA and helps target it into the nucleus. Although some strains of A. rhizogenes lack VirE2, they are pathogenic and transfer T-DNA efficiently. Instead, these bacteria express the GALLS protein, which is essential for their virulence. GALLS protein can complement an A. tumefaciens virE2 mutant for tumor formation, indicating that GALLS can substitute for VirE2. Unlike VirE2, GALLS contains ATP-binding and helicase motifs similar to those in TraA, a strand transferase involved in conjugation. Both GALLS and VirE2 contain nuclear localization sequences (NLS) and a C-terminal type IV secretion signal. Here we show that mutations in any of these domains abolished the ability of GALLS to substitute for VirE2.

This article has been cited by other articles:

• Gelvin, S. B. (2009). Agrobacterium in the Genomics Age. Plant Physiol. 150: 1665-1676 [Full Text]  
• Hodges, L. D., Lee, L.-Y., McNett, H., Gelvin, S. B., Ream, W. (2009). The Agrobacterium rhizogenes GALLS Gene Encodes Two Secreted Proteins Required for Genetic Transformation of Plants. J. Bacteriol. 191: 355-364 [Abstract] [Full Text]