The solution structure of type III effector protein AvrPto reveals conformational and dynamic features important for plant pathogenesis.
Pseudomonas syringae pv. tomato, the causative agent of bacterial speck disease of tomato, uses a type III secretion system (TTSS) to deliver effector proteins into the host cell. In resistant plants, the bacterial effector protein AvrPto physically interacts with the host Pto kinase and elicits antibacterial defense responses. In susceptible plants, which lack the Pto kinase, AvrPto acts as a virulence factor to promote bacterial growth. The solution structure of AvrPto reveals a functional core consisting of a three-helix bundle motif flanked by disordered N- and C-terminal tails. Residues required for Pto binding lie in a 19 residue Omega loop. Modeling suggests a hydrophobic patch involving the activation loop of Pto forms a contact surface with the AvrPto Omega loop and that helix packing mediates interactions between AvrPto and putative virulence targets Api2 and Api3. The AvrPto structure has a low stability that may facilitate chaperone-independent secretion by the TTSS.
Wulf
Jennifer
J
Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.
Pascuzzi
Pete E
PE
Fahmy
Amr
A
Martin
Gregory B
GB
Nicholson
Linda K
LK
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018551:Solanum lycopersicum / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000378:metabolism; D044224:Pseudomonas syringae / Q000235:genetics / Q000378:metabolism*; D040681:Structural Homology, Protein; D013329:Structure-Activity Relationship
D001426:Bacterial Proteins; D010940:Plant Proteins; C081695:avrPto protein, Pseudomonas syringae; C084354:Pto protein, Lycopersicon; D017346:Protein Serine-Threonine Kinases