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--- bacteria:t3e:xopi [2020/07/08 18:50]
rkoebnik [Biological function]
+++ bacteria:t3e:xopi [2020/07/09 10:16] (current)
rkoebnik
@@ Line 18: / Line 18: @@
 === (Experimental) evidence for being a T3E ===
-The transcripts of XopI were amplified from //Xcv// derivative 85* strain, which expresses a constitutively active HrpG point mutant resulting in constitutive expression of the T3S system, suggesting co‐expression with T3S genes (Schulze //et al//., 2012). To investigate whether //xopI// was indeed T3SS dependently secreted and translocated into the plant cell, a translational fusion with the reporter protein AvrBs3D2, a derivative of the TAL effector AvrBs3 which lacks a T3S and translocation signal, was performed. Fusion of a functional T3S signal to AvrBs3D2 enables its translocation and thus the induction of the HR in pepper cultivar ECW-30R plants that harbor the corresponding resistance gene //Bs3//. When the bacteria were incubated in T3S medium, XopI<sub>1–140</sub>-AvrBs3D2 was detected in the culture supernatant of strain 85*, but not of 85*D//hrcV//, by an AvrBs3-specific antibody. These results demonstrate that the XopI effector contained functional T3S signals in the N-terminal regions (Schulze //et al//., 2012) To test for T3SS-dependent translocation, //Xcv// strains 85* and 85*D//hrcV// expressing avrBs3D2 or //xopI// fusion were inoculated into leaves of AvrBs3-responsive pepper plants (ECW-30R) and the nearisogenic susceptible pepper line ECW, which lacks the //Bs3// resistance gene. Derivatives of strain 85* expressing XopI<sub>1–140</sub>-AvrBs3D2 induced the HR in ECW-30R, but not in ECW. No HR induction was observed in plants infected with derivatives of strain 85*D//hrcV//. Taken together, these findings confirm the T3SS secretion and translocation of XopI, and thus their nature as T3Es.
+The transcripts of XopI were amplified from //Xcv// derivative 85* strain, which expresses a constitutively active HrpG point mutant resulting in constitutive expression of the T3S system, suggesting co‐expression with T3S genes (Schulze //et al//., 2012). To investigate whether //xopI// was indeed T3SS dependently secreted and translocated into the plant cell, a translational fusion with the reporter protein AvrBs3Δ2, a derivative of the TAL effector AvrBs3 which lacks a T3S and translocation signal, was performed. Fusion of a functional T3S signal to AvrBs3Δ2 enables its translocation and thus the induction of the HR in pepper cultivar ECW-30R plants that harbor the corresponding resistance gene //Bs3//. When the bacteria were incubated in T3S medium, XopI<sub>1–140</sub>-AvrBs3Δ2 was detected in the culture supernatant of strain 85*, but not of 85*Δ//hrcV//, by an AvrBs3-specific antibody. These results demonstrate that the XopI effector contained functional T3S signals in the N-terminal regions (Schulze //et al//., 2012) To test for T3SS-dependent translocation, //Xcv// strains 85* and 85*Δ//hrcV// expressing avrBs3Δ2 or //xopI// fusion were inoculated into leaves of AvrBs3-responsive pepper plants (ECW-30R) and the near-isogenic susceptible pepper line ECW, which lacks the //Bs3// resistance gene. Derivatives of strain 85* expressing XopI<sub>1–140</sub>-AvrBs3Δ2 induced the HR in ECW-30R, but not in ECW. No HR induction was observed in plants infected with derivatives of strain 85*Δ//hrcV//. Taken together, these findings confirm the T3SS secretion and translocation of XopI, and thus their nature as T3Es.
 Translocation class; classification based on HpaB dependence (Büttner //et al.//, 2006).
@@ Line 36: / Line 36: @@
 XopR and XopS belong to //Xcv// translocation class A, comprising T3Es whose translocation into plant cells is completely dependent on HpaB, whereas XopB, XopG, **XopI**, XopK, XopM and XopV were assigned to class B, because they are still translocated in the absence of HpaB (Büttner //et al.//, 2006). Both new class A effectors lack homology to known proteins or motifs, so that their molecular function remains elusive. By contrast, the class B effectors comprise the putative enzyme XopG, a member of the HopH family of putative zinc metalloproteases. Other effectors possess interesting features, for example XopI contains an F‐box motif typical for eukaryotic proteins playing a role in the ubiquitin‐26S proteasome system (UPS). The UPS controls protein stability in eukaryotes and appears to be a favorable target for many T3Es, for example members of the GALA family, which strongly contribute to the virulence of //R. solanacearum// and the E3 ubiquitin ligase AvrPtoB from //P. syringae.//
 ===== Conservation =====

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