Distribution and phylogeny of the blue light receptors aureochromes in eukaryotes

Abstract

The new type blue light (BL) receptor aureochrome (AUREO) was recently discovered in a stramenopile alga, Vaucheria (Takahashi et al. Proc Natl Acad Sci USA 104(49):19625-19630, 2007). AUREO has a bZIP (basic region/leucine zipper) and BL-sensing light-oxygen-voltage (LOV) domain and functions as a BL-activated transcription factor. It mediates BL-induced branching and regulates the development of the sex organ in V. frigida. Although AUREO sequences have previously been found in Fucus and some diatoms, here we report that AUREO orthologs are commonly conserved in photosynthetic stramenopiles. Five AUREO orthologs were isolated from three stramenopile genera (Fucus, Ochromonas, and Chattonella). By BLAST search, several AUREO sequences were also detected in genomes in Aureococcus anophagefferens (Pelagophyceae). However, AUREO was not found in heterotrophic stramenopiles or in closely related phyla, such as haptophytes and cryptophytes, or in green plants. Stramenopiles do not possess phototropin, the well-known BL receptor for phototropism of green plants. From comparative analysis of LOV domains, together with kinship analysis of AUREO bZIP domains, AUREO can be regarded as the BL receptor specific to phototrophic stramenopiles. The evolution of AUREO and the phylogeny of LOV domains in stramenopiles and green plants are discussed.

AUREOCHROME1a-Mediated Induction of the Diatom-Specific Cyclin dsCYC2 Controls the Onset of Cell Division in Diatoms (Phaeodactylum tricornutum)

“…Screening for interactors of the dsCYC2 promoter yielded two transcription factors belonging to the bZIP transcription factor family: AUREO1a and bZIP10. Of particular interest is AUREO1a, which belongs to the AUREOCHROME family of blue light photoreceptors in photosynthetic stramenopiles (Takahashi et al, 2007;Ishikawa et al, 2009). AUREOCHROMES typically possess an N-terminal bZIP domain expected to be involved in dimerization and DNA binding and a C-terminal LOV domain thought to act as a photosensor (Takahashi et al, 2007;Toyooka et al, 2011).…”

Algal photoreceptors: in vivo functions and potential applications

“…Evanescens (Phaeophyceae), Chattonella antiqua (Raphidophyceae), Nannochloropsis gaditana CCMP526 (Eustigmatophyceae), Ochromonas danica (Chrysophyceae), Phaeodactylum tricornutum (Bacillariophyceae), Thalassiosira pseudonana (Coscinodiscophyceae) and Thalassiosira oceanica (Coscinodiscophyceae) (Armbrust et al 2004;Bowler et al 2008;Cock et al 2010;Ishikawa et al 2009;Lommer et al 2012;Radakovits et al 2012;Rayko et al 2010) (Fig. 3a).…”

Blue Light-induced Dimerization of Monomeric Aureochrome-1 Enhances Its Affinity for the Target Sequence

“…It was therefore suggested that the AUREO proteins function as BL-regulated transcription factors (14). AUREO orthologs have been found only in photosynthetic stramenopiles such as brown algae, some diatoms, Ochromonas, Chattonella, and Aureococcus (18). Interestingly, the AUREO proteins lack the effector domains at their C terminus and the Glu-Lys salt bridges that are conserved in most other LOV domains.…”