6wlp | pdb_00006wlp
Crystal Structure of the ZTL light-state mimic G46S
Structural highlights
FunctionADO1_ARATH Component of an E3 ubiquitin ligase complex that plays a central role in blue light-dependent circadian cycles. Acts as a blue light photoreceptor, due to the presence of FMN, that mediates light-regulated protein degradation of critical clock components by targeting them to the proteasome complex. The SCF(ADO1) E3 ubiquitin ligase complex is involved in the regulation of circadian clock-dependent processes including the transition to flowering time, hypocotyl elongation, cotyledons and leaf movement rhythms. APRR1/TOC1 and APRR5, but not 'GIGANTEA', are proteolytic substrates of this ubiquitin ligase complex. Blue light enhances cooperative stabilization of 'GIGANTEA' and ADO1/ZTL, leading to amplification and sharpening of the expression profile of APRR1/TOC1. ADO1/ZTL interacts with ADO3, preventing the interaction of ADO3 with CDF1.[1] [2] [3] [4] [5] [6] [7] [8] [9] Publication Abstract from PubMedPlants measure light quality, intensity, and duration to coordinate growth and development with daily and seasonal changes in environmental conditions; however, the molecular details linking photochemistry to signal transduction remain incomplete. Two closely related light, oxygen, or voltage (LOV) domain-containing photoreceptor proteins, ZEITLUPE (ZTL) and FLAVIN-BINDING, KELCH REPEAT, F-BOX 1 (FKF1), divergently regulate the protein stability of circadian clock and photoperiodic flowering components to mediate daily and seasonal development. Using structural approaches, we identified that mutations at the Gly46 position led to global rearrangements of the ZTL dimer interface in the isolated ZTL-LOV domain. Specifically, G46S and G46A variants induce a 180 degrees rotation about the ZTL-LOV dimer interface that is coupled to ordering of N- and C-terminal signaling elements. These conformational changes hinge upon rotation of a C-terminal Gln residue (Gln154) analogous to that present in light-state structures of ZTL. In contrast to other LOV proteins, a Q154L variant retains light-state interactions with GIGANTEA (GI), thereby indicating N5 protonation is not required for ZTL signaling. The results presented herein confirm a divergent signaling mechanism within ZTL, whereby steric and electronic effects following adduct formation can be sufficient for signal propagation in LOV proteins containing a Gly residue at position 46. Examination of bacterial LOV structures with Gly residues at the equivalent position suggests that mechanisms of signal transduction in LOV proteins may be fluid across the LOV protein family. Steric and Electronic Interactions at Gln154 in ZEITLUPE Induce Reorganization of the LOV Domain Dimer Interface.,Pudasaini A, Green R, Song YH, Blumenfeld A, Karki N, Imaizumi T, Zoltowski BD Biochemistry. 2021 Jan 19;60(2):95-103. doi: 10.1021/acs.biochem.0c00819. Epub, 2020 Dec 18. PMID:33337855[10] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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