4hhd | pdb_00004hhd
2.75 Angstrom resolution crystal structure of the A. thaliana LOV2 domain with an extended N-terminal A' helix (cryo dark structure)
Structural highlights
Function[PHOT1_ARATH] Protein kinase that acts as a blue light photoreceptor in a signal-transduction pathway for photo-induced movements. Required for blue light mediated mRNA destabilization. Mediates calcium spiking of extracellular origin in response to a low rate of blue light. Also mediates rapid membrane depolarization and growth inhibition in response to blue light. Necessary for root phototropism. Involved in hypocotyl phototropism under a low rate but not under a high rate of blue light. Contributes to the chloroplast accumulation but seems not to be required for chloroplast translocation. Regulates stomata opening and photomorphogenesis response of leaf tissue. Confers sensitivity to drought. Not involved in hypocotyl elongation inhibition, anthocyanin accumulation or cotyledon opening.[1] [2] [3] [4] [5] [6] [7] [8] Publication Abstract from PubMedA key role in signal transduction and dimerization mediated by Per-Arnt-Sim (PAS) domains is played by alpha-helical linkers that flank the structurally similar alpha/beta cores of these domains. However, crystal-packing forces and the different construct lengths and sequences of the PAS domains influence the final length and orientation of the linkers relative to the core and create uncertainty in the exact mechanism of the linker function. Thus, structural characterization and comparison of the linkers within isolated PAS-domain constructs and/or full-length PAS-containing proteins is important for clarification of the mechanism. The plant blue-light photoreceptors phototropins possess two N-terminal flavin mononucleotide-based light, oxygen or voltage (LOV) domains (LOV1 and LOV2) that comprise a subclass of the PAS family and one C-terminal serine/threonine kinase domain whose enzymatic activity is regulated by blue light. The dark-adapted state crystal structures of the Arabidopsis thaliana phototropin 1 and phototropin 2 LOV1-domain constructs flanked by an N-terminal A'alpha helix and the structure of the phototropin 2 core LOV2 domain are known. Here, the crystal structure of the A. thaliana phototropin 1 LOV2 domain has been determined in its dark-adapted state. The core is flanked by an N-terminal A'alpha helix and a C-terminal Jalpha helix similar to those in the previously reported structure of Avena sativa phototropin 1 LOV2. In contrast to the monomeric A. sativa LOV2, A. thaliana LOV2 is a dimer in which two A'alpha helices adopt a scissor-like orientation at the dimer interface and form a short alpha-helical coiled coil. The Jalpha helix predominantly interacts with the beta-sheet and plays a role in coiled-coil formation and dimerization. Coiled-coil dimerization of the LOV2 domain of the blue-light photoreceptor phototropin 1 from Arabidopsis thaliana.,Halavaty AS, Moffat K Acta Crystallogr Sect F Struct Biol Cryst Commun. 2013 Dec;69(Pt 12):1316-21., doi: 10.1107/S1744309113029199. Epub 2013 Nov 28. PMID:24316821[9] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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