| dc.description.abstract | The phytohormone jasmonates (JAs) regulate fundamental plant processes; such
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as the anthocyanin accumulation during ripening of strawberry, a non-climacteric fruit model.
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Jasmonoyl-isoleucine (JA-Ile), one of the bioactive JA molecules, mediates binding of the JAZ
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repressor protein to COI1, an F-box protein forming the SCFCOI1 ubiquitin E3 ligase complex, in
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Arabidopsis. The COI1-JA-Ile-JAZ complex initiates the JA-signaling pathway leading to early
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jasmonate responses. Most of Arabidopsis JAZs contain a degron sequence at the Jas domain
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responsible for interaction with COI1 and JA-Ile. The woodland strawberry (Fragaria vesca) is a
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model plant for the Rosaceae family, in which the JA-signaling pathway is poorly understood at
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the molecular level. The aim of this work was to understand the molecular basis of the
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interaction between the F. vesca COI1 (FvCOI1) and JAZ1 (FvJAZ1) or JAZ8 (FvJAZ8)
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mediated by JA-Ile.
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Methods. Multiple alignments of amino acid sequences and phylogenetic analyses were
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performed for FvCOI1 and FvJAZ1/8 and their ortholog sequences. The FvCOI1 and FvJAZ1/8
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3D structures were built by homology modeling methods, which were further refined and
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validated by molecular dynamics simulation (MDS). A molecular docking approach along with
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MDS analysis were used to understand the interaction capacity between a putative degron-like
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present in FvJAZ1 and FvJAZ8 with the FvCOI1-JA-Ile and FvCOI1-JA complexes.
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Results. FvCOI1 and FvJAZ1/8 showed high and moderate identity, respectively, with the
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corresponding ortholog proteins from other plant species including apple, grape, tomato and
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Arabidopsis. The resulting FvCOI1 structural model showed that the F-box and LRR domains
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were highly similar to that described in Arabidopsis COI1 (AtCOI1) crystal structure.
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Unexpectedly, we found that FvJAZ1 has a variant IPMQRK sequence respect to the canonical
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LPIAR(R/K) degron sequence observed in AtJAZ1. The MDS results showed that the FvCOI1-
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JA-Ile-FvJAZ1 complex was the most stable among all the analyzed ones, and the IPMQRK
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peptide of FvJAZ1 interacted directly with FvCOI1 and JA-Ile. In contrast, FvJAZ8 did not show
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a direct interaction with those two components, as expected from previous experimental results
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for the ortholog AtJAZ8.
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Discussion. The present research provides novel insight into the molecular interactions between
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key JA-signaling components in the model plant F. vesca. Remarkably, we characterized the
PeerJ Preprints | https://doi.org/10.7287/peerj.preprints.2772v2 | CC BY 4.0 Open Access | rec: 14 Jan 2018, publ: 14 Jan 2018
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IPMQRK sequence present in FvJAZ1, a putative variant 58
of the canonical degron previously
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described in AtJAZ1. We propose that the FvCOI1-JA-Ile-FvJAZ1 complex is stable, and that
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the degron-like sequence present in FvJAZ1 interacts in a steady manner with FvCOI1-JA-Ile.
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Up to now, this is the first structural characterization of molecular interactions that may be
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occurring between the core components of the JA-Ile perception complex in a fleshy fruit-related
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species. | |
