A new functional JAZ degron sequence in strawberry JAZ1 revealed by structural and interaction studies on the COI1–JA-Ile/COR–JAZs complexes

Abstract

The phytohormone jasmonoyl-isoleucine (JA-Ile) regulates fundamental plant processes as developmental and defense responses. JA-Ile mediates the interaction between the F-box protein COI1 (part of the SCF COI1 E3 ubiquitin ligase) and a JAZ repressor leading to early jasmonate responses. The Arabidopsis JAZ1 protein contains the canonical LPIARR degron sequence, which is responsible for the stabilization of the AtCOI1-JA-Ile-AtJAZ1 complex. In strawberry (Fragaria × ananassa) JAZ family was described at the transcriptional level during fruit development but the information about the interaction mode of this complex is still scarce at the molecular level. To gain insight into the strawberry JA-Ile receptor complex, we evaluated the interaction at the structural level, and protein models were built and analyzed for FaCOI1 and FaJAZ1, FaJAZ8.1, and FaJAZ10. The interaction between FaCOI1 and FaJAZ1, FaJAZ8.1 and FaJAZ10 were explored using several ligands, through molecular docking and molecular dynamics (MD) simulations, finding the strongest interaction with (+)-7-iso-JA-Ile than other ligands. Additionally, we tested interactions between FaCOI1 and FaJAZs by yeast two-hybrid assays in the presence of coronatine (COR, a JA-Ile mimic). We detected strong COR-dependent interactions between FaCOI1 and FaJAZ1. Interestingly, FaJAZ1 contains a new non-canonical (IPMQRK) functional degron sequence, in which Arg and Lys are the key residues for maintaining the interaction of the FaCOI1-COR-FaJAZ1 complex as we observed in mutated versions of the FaJAZ1 degron. Phylogenetic analysis showed that the IPMQRK degron is only present in orthologs belonging to the Rosoideae but not in other Rosaceae subfamilies. Together, this study uncovers a new degron sequence in plants, which could be required to make an alternative and functional JA-Ile perception complex in strawberry. Jasmonates (JAs) are phytohormones that regulate development and stress processes in land plants 1-3. The (+)-7-iso-jasmonoyl-l-isoleucine (JA-Ile) is the bioactive jasmonate in Arabidopsis 4 and accumulates at the early stages of development in grape and strawberry fruits 5,6. The bacterial phytotoxin coronatine (COR) is structurally and functionally analogous to JA-Ile 7 .

Interactions of JAZ Repressors with Anthocyanin Biosynthesis-Related Transcription Factors of Fragaria × ananassa

“…The activation of JA-signal transduction triggers the regulation of developmental processes and responses to multiple stresses [23,39,40]. Essentially, the JA-signaling pathway regulates other molecular pathways by protein-protein interactions mediated by JAZ repressors and MYC TFs, and it is well described in Arabidopsis [29][30][31][32] and starting to be known in strawberry [15,27,28,39]. On the one hand, F. vesca and F. × ananassa contain a conserved perception mechanism at the structural and functional levels [27,28].…”

“…Essentially, the JA-signaling pathway regulates other molecular pathways by protein-protein interactions mediated by JAZ repressors and MYC TFs, and it is well described in Arabidopsis [29][30][31][32] and starting to be known in strawberry [15,27,28,39]. On the one hand, F. vesca and F. × ananassa contain a conserved perception mechanism at the structural and functional levels [27,28]. However, on the other hand, components for downstream JA-signaling pathway like MYC or JAM TFs have only been characterized at the transcriptional level in F. × ananassa [39].…”

“…In this sense, the molecular JAs signaling pathway is involved in the JA-Ile sensing mechanism and the activation of JA responses [24,25]. The perception of JA-Ile is mediated by CORONATINE INSENSITIVE 1 (COI1) protein and JASMONATE ZIM-DOMAIN (JAZ) repressors, which interact when JA-Ile levels increase [23,26], and this mechanism is conserved in Fragaria vesca L. and F. × ananassa [27,28]. Then, JAZ proteins are degraded by the 26S proteasome, and MYC TFs are released to activate the expression of JA-responsive genes in Arabidopsis [29][30][31][32].…”

Extended JAZ degron sequence for plant hormone binding in jasmonate co-receptor of tomato SlCOI1-SlJAZ

“…In silico docking simulation studies using the crystal structure of Arabidopsis COI1-JA-Ile-JAZ1 have previously enabled the study of the JA-Ile binding mode of the COI1-JAZ co-receptor of other plant species, such as Phaseolus lunatus, Eleusine coracana (L.) Gaertn, Fragaria vesca, and Fragaria × ananassa. 20,21,28,29 The contribution of the extended JAZ degron sequence to SlCOI1-JAIle-SlJAZ complex formation was examined by comparing the crystal structure of Arabidopsis COI1-JAIle-JAZ1 with the in silico interaction models of SlCOI1-JAIle-SlJAZ1 and SlCOI1-JAIle-SlJAZ5, which have an affinity for JA-Ile. A homology model of SlCOI1 was obtained with MOE based on the crystal structure of AtCOI1 complexed with JA-Ile and using AtJAZ1 (PDB ID: 3OGL) as a template (the sequence identity of SlCOI1 and AtCOI1 is 68.1%).…”

“…The JAZ degron sequence is highly conserved among plant species, except for the two non-canonical degron sequences IPMQRK of FaJAZs found in the strawberry plant Fragaris X ananassa, and MPIARK of EcJAZ1 found in finger millet Eleusine coracana (L.) Gaertn. [19][20][21] Small differences in the Arabidopsis JAZ degron sequences (identity 37.0% in Figure 1a) are considered to account for the difference in affinity (KD) between JAZ and COI1-JA-Ile. 22 However, the 12 JAZs of Solanum lycopersicum have a remarkably wellconserved JAZ degron sequence (V/L)P(Q/I)AR(R/K) (identity 46.6% in Figure 1a), suggesting their affinities (KD) for the SlCOI1-JA-Ile complex are very similar (Figure 1a).…”