Dataset Information

Pseudomonas syringae type III effector AvrPtoB is phosphorylated in plant cells on serine 258, promoting its virulence activity.

ABSTRACT: The Pseudomonas syringae pv. tomato protein AvrPtoB is translocated into plant cells via the bacterial type III secretion system. In resistant tomato leaves, AvrPtoB acts as an avirulence protein by interacting with the host Pto kinase and eliciting the host immune response. Pto-mediated immunity requires Prf, a Pto-interacting protein with a putative nucleotide-binding site and a region of leucine-rich repeats. In susceptible tomato plants, which lack either Pto or Prf, AvrPtoB acts as a virulence protein by promoting P. syringae pv. tomato growth and enhancing symptoms associated with bacterial speck disease. The N-terminal 307 amino acids of AvrPtoB (designated AvrPtoB(1-307)) are sufficient for these virulence activities and for Pto-mediated avirulence. We report that AvrPtoB is phosphorylated by a Pto- and Prf-independent kinase activity that is conserved in several plant species, including tomato (Solanum lycopersicum), Nicotiana benthamiana, and Arabidopsis thaliana. AvrPtoB(1-307) was phosphorylated in tomato protoplasts, and mass spectrometry identified serine 258 as the major in vivo phosphorylation site of this protein. An alanine substitution of Ser(258) resulted in the loss of virulence and the diminution of avirulence activity of AvrPtoB(1-307), whereas a phosphomimetic S258D mutant had activities similar to wild type AvrPtoB(1-307). These observations suggest that AvrPtoB has evolved to mimic a substrate of a conserved plant kinase, leading to enhancement of its virulence and avirulence activities in the host cell.

SUBMITTER: Xiao F

PROVIDER: S-EPMC2267685 | biostudies-literature | 2007 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Pseudomonas syringae type III effector AvrPtoB is phosphorylated in plant cells on serine 258, promoting its virulence activity.

Xiao Fangming F Giavalisco Patrick P Martin Gregory B GB

The Journal of biological chemistry 20070820 42

The Pseudomonas syringae pv. tomato protein AvrPtoB is translocated into plant cells via the bacterial type III secretion system. In resistant tomato leaves, AvrPtoB acts as an avirulence protein by interacting with the host Pto kinase and eliciting the host immune response. Pto-mediated immunity requires Prf, a Pto-interacting protein with a putative nucleotide-binding site and a region of leucine-rich repeats. In susceptible tomato plants, which lack either Pto or Prf, AvrPtoB acts as a virule ...[more]

PMID: 17711844

Similar Datasets

Project description:Resistance to bacterial speck disease in tomato is activated by the physical interaction of the host Pto kinase with either of the sequence-dissimilar type III effector proteins AvrPto or AvrPtoB (HopAB2) from Pseudomonas syringae pv. tomato. Pto-mediated immunity requires Prf, a protein with a nucleotide-binding site and leucine-rich repeats. The N-terminal 307 amino acids of AvrPtoB were previously reported to interact with the Pto kinase, and we show here that this region (AvrPtoB(1-307)) is sufficient for eliciting Pto/Prf-dependent immunity against P. s. pv. tomato. AvrPtoB(1-307) was also found to be sufficient for a virulence activity that enhances ethylene production and increases growth of P. s. pv. tomato and severity of speck disease on susceptible tomato lines lacking either Pto or Prf. Moreover, we found that residues 308-387 of AvrPtoB are required for the previously reported ability of AvrPtoB to suppress pathogen-associated molecular patterns-induced basal defenses in Arabidopsis. Thus, the N-terminal region of AvrPtoB has two structurally distinct domains involved in different virulence-promoting mechanisms. Random and targeted mutagenesis identified five tightly clustered residues in AvrPtoB(1-307) that are required for interaction with Pto and for elicitation of immunity to P. s. pv. tomato. Mutation of one of the five clustered residues abolished the ethylene-associated virulence activity of AvrPtoB(1-307). However, individual mutations of the other four residues, despite abolishing interaction with Pto and avirulence activity, had no effect on AvrPtoB(1-307) virulence activity. None of these mutations affected the basal defense-suppressing activity of AvrPtoB(1-387). Based on sequence alignments, estimates of helical propensity, and the previously reported structure of AvrPto, we hypothesize that the Pto-interacting domains of AvrPto and AvrPtoB(1-307) have structural similarity. Together, these data support a model in which AvrPtoB(1-307) promotes ethylene-associated virulence by interaction not with Pto but with another unknown host protein.

Dataset Information

Pseudomonas syringae type III effector AvrPtoB is phosphorylated in plant cells on serine 258, promoting its virulence activity.

Publications

Pseudomonas syringae type III effector AvrPtoB is phosphorylated in plant cells on serine 258, promoting its virulence activity.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets