naa a22 4500 530216752 CHVBK 20181027070834.0 cr unu---uuuuu 181027s2018 xx s 000 0 eng 10.1073/pnas.1811858115 doi (SERVAL)BIB_867649C2723F 30254172 pmid 000446764200036 isiid Distinct modes of derepression of an <i>Arabidopsis</i> immune receptor complex by two different bacterial effectors [Elektronische Daten] [Y. Ma, H. Guo, L. Hu, P.P. Martinez, P.N. Moschou, V. Cevik, P. Ding, Z. Duxbury, P.F. Sarris, JDG Jones] Plant intracellular nucleotide-binding leucine-rich repeat (NLR) immune receptors often function in pairs to detect pathogen effectors and activate defense. The &lt;i&gt;Arabidopsis&lt;/i&gt; RRS1-R-RPS4 NLR pair recognizes the bacterial effectors AvrRps4 and PopP2 via an integrated WRKY transcription factor domain in RRS1-R that mimics the effector's authentic targets. How the complex activates defense upon effector recognition is unknown. Deletion of the WRKY domain results in an RRS1 allele that triggers constitutive RPS4-dependent defense activation, suggesting that in the absence of effector, the WRKY domain contributes to maintaining the complex in an inactive state. We show the WRKY domain interacts with the adjacent domain 4, and that the inactive state of RRS1 is maintained by WRKY-domain 4 interactions before ligand detection. AvrRps4 interaction with the WRKY domain disrupts WRKY-domain 4 association, thus derepressing the complex. PopP2-triggered activation is less easily explained by such disruption and involves the longer C-terminal extension of RRS1-R. Furthermore, some mutations in RPS4 and RRS1 compromise PopP2 but not AvrRps4 recognition, suggesting that AvrRps4 and PopP2 derepress the complex differently. Consistent with this, a "reversibly closed" conformation of RRS1-R, engineered in a method exploiting the high affinity of colicin E9 and Im9 domains, reversibly loses AvrRps4, but not PopP2 responsiveness. Following RRS1 derepression, interactions between domain 4 and the RPS4 C-terminal domain likely contribute to activation. Simultaneous relief of autoinhibition and activation may contribute to defense activation in many immune receptors. Ma Y. aut Guo H. aut Hu L. aut Martinez P.P. aut Moschou P.N. aut Cevik V. aut Ding P. aut Duxbury Z. aut Sarris P.F. aut Jones JDG aut Proceedings of the National Academy of Sciences of the United States of America 115/41(2018), 10218-10227 115:41<10218-10227 2018 115 1 article serval SERVAL 700 1- Ma Y. aut SERVAL 700 1- Guo H. aut SERVAL 700 1- Hu L. aut SERVAL 700 1- Martinez P.P. aut SERVAL 700 1- Moschou P.N. aut SERVAL 700 1- Cevik V. aut SERVAL 700 1- Ding P. aut SERVAL 700 1- Duxbury Z. aut SERVAL 700 1- Sarris P.F. aut SERVAL 700 1- Jones JDG aut SERVAL 773 0- Proceedings of the National Academy of Sciences of the United States of America 115/41(2018), 10218-10227 115:41<10218-10227 2018 115 BK010053 XK010053 XK010000 SERVAL SERVAL SERVAL article