The Agrobacterium VirD5 protein hyperactivates the mitotic Aurora kinase in host cells

• Published in: The New phytologist Vol. 222; no. 3; pp. 1551 - 1560
• Main Authors: Zhang, Xiaorong, Hooykaas, Paul J. J.
• Format: Journal Article
• Language: English
• Published: England Wiley 01.05.2019; Wiley Subscription Services, Inc; John Wiley and Sons Inc
• Subjects: Agrobacterium tumefaciens; Agrobacterium tumefaciens - metabolism; Arabidopsis - growth & development; Arabidopsis - microbiology; Aurora kinase; Aurora Kinases - metabolism; Bacterial Proteins - chemistry; Bacterial Proteins - metabolism; Biocompatibility; Chromosome Segregation; Chromosomes; Deoxyribonucleic acid; DNA; Enzyme Activation; Error correction; Fluorescence; Host-Pathogen Interactions; Instability; Kinases; kinetochore; Kinetochores; Kinetochores - metabolism; Microtubules - metabolism; Mitosis; Nuclei (cytology); Pathogens; Phosphatase; Phosphorylation; Plant cells; Protein Binding; Proteins; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - metabolism; Segregation; Spindle Apparatus - metabolism; Stability; Substrates; Toxicity; Virulence; Yeast; Yeasts; Agrobacterium tumefaciens; kinetochore; Aurora kinase; virulence; mitosis
• ISSN: 0028-646X; 1469-8137
• DOI: 10.1111/nph.15700

Aided by translocated virulence proteins, Agrobacterium tumefaciens transforms plant cells with oncogenic T-DNA. In the host cells the virulence protein VirD5 moves to the nucleus, where it becomes localized at the kinetochores, and disturbs faithful chromosome segregation, but the molecular mechanism underlying this remains unknown. To gain more insight, we screened amongst the kinetochore proteins for VirD5 interactors using bimolecular fluorescence complementation assays, and tested chromosome segregation in yeast cells. We found that VirD5 interacts with the conserved mitotic Aurora kinase Ipl1 in yeast and likewise with plant Aurora kinases. In vitro VirD5 was found to stimulate the activity of Ipl1. Phosphorylation of substrates by Ipl1 in vivo is known to result in the detachment between kinetochore and spindle microtubule. This is necessary for error correction, but increased Ipl1/Aurora kinase activity is known to cause spindle instability, explaining enhanced chromosome mis-segregation seen in the presence of VirD5. That activation of the Ipl1/Aurora kinase at least partially underlies the toxicity of VirD5 became apparent by artificial boosting the activity of the specific counteracting phosphatase Glc7 in vivo, which relieved the toxicity. These findings reveal a novel mechanism by which a pathogenic bacterium manipulates host cells.