Molecular characterization of proteolytic cleavage sites of the Pseudomonas syringae effector AvrRpt2

Abstract

Prions are unprecedented infectious pathogens that cause a group of invariably fatal neurodegenerative diseases by an entirely novel mechanism. Prion diseases may present as genetic, infectious, or sporadic disorders, all of which involve modification of the prion protein (PrP). Bovine spongiform encephalopathy (BSE), scrapie of sheep, and Creutzfeldt-Jakob disease (CJD) of humans are among the most notable prion diseases. Prions are transmissible particles that are devoid of nucleic acid and seem to be composed exclusively of a modified protein (PrP Sc ). The normal, cellular PrP (PrP C ) is converted into PrP Sc through a posttranslational process during which it acquires a high ␤-sheet content. The species of a particular prion is encoded by the sequence of the chromosomal PrP gene of the mammals in which it last replicated. In contrast to pathogens carrying a nucleic acid genome, prions appear to encipher strain-specific properties in the tertiary structure of PrP Sc . Transgenetic studies argue that PrP Sc acts as a template upon which PrP C is refolded into a nascent PrP Sc molecule through a process facilitated by another protein. Miniprions generated in transgenic mice expressing PrP, in which nearly half of the residues were deleted, exhibit unique biological properties and should facilitate structural studies of PrP Sc . While knowledge about prions has profound implications for studies of the structural plasticity of proteins, investigations of prion diseases suggest that new strategies for the prevention and treatment of these disorders may also find application in the more common degenerative diseases.

The Pseudomonas syringae Type III Effector AvrRpt2 Promotes Pathogen Virulence via Stimulating Arabidopsis Auxin/Indole Acetic Acid Protein Turnover

“…These data indicate that Cys protease activity is required for AvrRpt2 to stimulate the auxin response. Consistent with previous reports (Axtell and Staskawicz, 2003;Chisholm et al, 2005), H208A and C122A mutants accumulated as unprocessed proteins (due to their proteolytic deficiency) to a level comparable to that of wild-type AvrRpt2 (Fig. 3, B and C; Supplemental Fig.…”

“…AvrRpt2 encodes a Cys protease that cleaves itself and several host proteins, and this activity is essential for AvrRpt2 to trigger defense responses mediated by RPS2 (Axtell et al, 2003;Chisholm et al, 2005). Our Figure 6.…”

“…Protein structural prediction and functional analyses indicated that AvrRpt2 is a Cys protease that is autoprocessed inside the plant cell, where it further cleaves several host proteins (Axtell et al, 2003;Chisholm et al, 2005). The conserved residues comprising the catalytic Figure 1.…”

“…Transient expression of AvrRpt2 in protoplasts promotes auxin-responsive gene expression (Chen et al, 2007). AvrRpt2 is a Cys protease that is active in plant cells, and several host targets of AvrRpt2 have been identified (Axtell et al, 2003;Chisholm et al, 2005). To understand the underlying mechanism through which AvrRpt2 alters auxin physiology, we tested whether AvrRpt2 could modulate the key components in auxin signaling.…”

RPG1-B-Derived Resistance to AvrB-Expressing Pseudomonas syringae Requires RIN4-Like Proteins in Soybean

“…GmRIN4c and GmRIN4d were approximately 91% identical to each other, approximately 46%/48% identical to AtRIN4, respectively, approximately 49% identical to the two LsRIN4 proteins, and approximately 47% identical to SlRIN4. All four GmRIN4 proteins contained several conserved domains present in AtRIN4, including those involved in binding to AvrB, an amino acid sequence required for AvrRpt2-mediated cleavage, and a putative palmitoylation site for plasma membrane localization (Chisholm et al, 2005;Kim et al, 2005a;Takemoto andJones, 2005, Desveaux et al, 2007;Fig. 1A).…”