Structure of a Native-like Aureochrome 1a LOV Domain Dimer from Phaeodactylum tricornutum

Abstract

Light-oxygen-voltage (LOV) domains absorb blue light for mediating various biological responses in all three domains of life. Aureochromes from stramenopile algae represent a subfamily of photoreceptors that differs by its inversed topology with a C-terminal LOV sensor and an N-terminal effector (basic region leucine zipper, bZIP) domain. We crystallized the LOV domain including its flanking helices, A'α and Jα, of aureochrome 1a from Phaeodactylum tricornutum in the dark state and solved the structure at 2.8 Å resolution. Both flanking helices contribute to the interface of the native-like dimer. Small-angle X-ray scattering shows light-induced conformational changes limited to the dimeric envelope as well as increased flexibility in the lit state for the flanking helices. These rearrangements are considered to be crucial for the formation of the light-activated dimer. Finally, the LOV domain of the class 2 aureochrome PtAUREO2 was shown to lack a chromophore because of steric hindrance caused by M301.

Signal transduction in photoreceptor histidine kinases

“…65,68 In general, for different LOV receptors these initial light-induced conformational changes consistently culminate in a destabilization of the interaction between the outer face of the β-sheet and N-and C-terminal ancillary elements packed against it, often causing their detachment. This is most prominently evidenced in the dissociation and unfolding of the Jα helix in phototropin LOV sensors 57 but is also reflected in the DNA-binding LOV receptors aureochromes 69,70 and EL222, 71 Neurospora crassa Vivid, 39,67 RGS-LOV proteins, 72 a recently discovered RNAbinding LOV receptor, 38 and in the monomeric LOV sensor histidine kinase EL346. 6 Applied to YF1 as a paradigm for the more prevalent dimeric SHKs, the following scenario emerges.…”

Controlling Cells with Light and LOV

“…These include, besides the structurally similar At LOV2 domain from Arabidopsis thaliana phototropin‐1, the A. thaliana flavin‐binding kelch repeat f‐box 1 (FKF1), the VIVID LOV domain from Neurospora crassa , the Erythrobacter litoralis EL222 domain, the Vaucheria frigida aureochrome1 LOV, and the Rhodobacter sphaeroides ( Rs )LOV domain. While we kindly refer readers to the extensive literature on details about their structures and photocycles, we will discuss their notable properties in context of optogenetic applications.…”

Engineering genetically-encoded tools for optogenetic control of protein activity

“…For such targets, light can be used to modulate protein oligomeric state, thus inducing signaling or other protein activity. To this end, target proteins can be fused to photosensory domains that undergo light-induced homo-dimerization or oligomerization such as VVD [12,13], Arabidopsis thaliana cryptochrome 2 (CRY2) [14–18], or the LOV domains from Vaucheria frigida aureochrome1 (VfAU1-LOV) [19,20] or Phaeodactylum tricornutum aureochrome1a (PtAu1a) [21,22]. Alternatively, two different targets can be fused to domains that heterodimerize in light, such as Arabidopsis thaliana PhyB/PIF [23,24], FKF1/GIGANTEA [25], CRY2/CIB1 [26], TULIPs [6], iLIDs [7], Magnets [8], or BphP1/RpsR2 [9] (Fig.…”