The Aureochrome Photoreceptor PtAUREO1a Is a Highly Effective Blue Light Switch in Diatoms

Mann, Marcus; Serif, Manuel; Wrobel, Thomas; Eisenhut, Marion; Madhuri, Shvaita; Flachbart, Samantha; Weber, Andreas P.M.; Lepetit, Bernard; Wilhelm, Christian; Kroth, Peter G.

doi:10.1016/j.isci.2020.101730

Cited by 16 publications

(10 citation statements)

References 67 publications

(98 reference statements)

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“…Interestingly, when comparing blue and ‘white’ light treatments of the same PUR (5.8 and 11.7 µmol photons m −2 s −1 PUR), we did not observe (apart from a consistent but not significant increase in NPQ) the blue light-triggered high-light acclimation previously described in temperate diatoms [ 38 , 63 ] and shown to be controlled by the aureochrome blue light photoreceptor family [ 64 , 65 ], although F. cylindrus does possess aureochromes [ 66 ]. F. cylindrus is usually found to be abundant at the sea-ice bottom horizon and underneath ice [ 51 , 53 ] where blue wavelengths dominate [ 43 , 44 ].…”

Section: Discussioncontrasting

confidence: 46%

Potential for the Production of Carotenoids of Interest in the Polar Diatom Fragilariopsis cylindrus

et al. 2022

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Carotenoid xanthophyll pigments are receiving growing interest in various industrial fields due to their broad and diverse bioactive and health beneficial properties. Fucoxanthin (Fx) and the inter-convertible couple diadinoxanthin–diatoxanthin (Ddx+Dtx) are acknowledged as some of the most promising xanthophylls; they are mainly synthesized by diatoms (Bacillariophyta). While temperate strains of diatoms have been widely investigated, recent years showed a growing interest in using polar strains, which are better adapted to the natural growth conditions of Nordic countries. The aim of the present study was to explore the potential of the polar diatom Fragilariopsis cylindrus in producing Fx and Ddx+Dtx by means of the manipulation of the growth light climate (daylength, light intensity and spectrum) and temperature. We further compared its best capacity to the strongest xanthophyll production levels reported for temperate counterparts grown under comparable conditions. In our hands, the best growing conditions for F. cylindrus were a semi-continuous growth at 7 °C and under a 12 h light:12 h dark photoperiod of monochromatic blue light (445 nm) at a PUR of 11.7 μmol photons m−2 s−1. This allowed the highest Fx productivity of 43.80 µg L−1 day−1 and the highest Fx yield of 7.53 µg Wh−1, more than two times higher than under ‘white’ light. For Ddx+Dtx, the highest productivity (4.55 µg L−1 day−1) was reached under the same conditions of ‘white light’ and at 0 °C. Our results show that F. cylindrus, and potentially other polar diatom strains, are very well suited for Fx and Ddx+Dtx production under conditions of low temperature and light intensity, reaching similar productivity levels as model temperate counterparts such as Phaeodactylum tricornutum. The present work supports the possibility of using polar diatoms as an efficient cold and low light-adapted bioresource for xanthophyll pigments, especially usable in Nordic countries.

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Section: Discussioncontrasting

confidence: 46%

Potential for the Production of Carotenoids of Interest in the Polar Diatom Fragilariopsis cylindrus

et al. 2022

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“…Absence of phototropins in photosynthetic heterokontophyta makes aureochrome vital BL-responsive photoreceptors besides cryptochromes. The direct BL-dependent DNA binding ability of aureochrome without the need of an elaborate signaling cascade enables aureochrome to bring about faster changes in gene expression under fluctuating light conditions (Mann et al, 2020). While a substantial amount of literature including multiple papers on structural information (Mitra et al, 2012) (Banerjee et al, 2016) (Hepp et al, 2020) (Heintz & Schlichting, 2016), is found against the LOV sensors of aureochromes, structure based mechanistic insights is scarce for the effector bZIPs.…”

Section: Discussionmentioning

confidence: 99%

“…Heterokontophyta typically lacks phototropins (Rayko et al, 2010) - one of the major LOV photoreceptors in land plants. However, aureochrome is known to aid in the optimization of photosynthesis (Mann et al, 2020) under varied light conditions. The broad spectrum functions of aureochromes include promotion of high light acclimation, photo protection in diatoms (Costa et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Basic Leucine Zippers: Aureochromes Versus the Rest

Khamaru

Deb

Mitra

2022

Preprint

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The photoreceptor cum transcription factors, Aureochromes, is present exclusively in marine photosynthetic algae. Co-existence of Light-Oxygen-Voltage (LOV) sensor and basic leucine zipper (bZIP) effector in aureochromes is unique -- no other photoreceptors barring aureochromes are known to possess bZIP as effector. The ability of aureochromes to participate in diverse biological activities, inverse topological arrangement make them a model protein not only to study light-dependent gene expression or transcriptional regulation but also as potential optogenetic scaffold. While detailed structural information is available for the LOV sensor, 3D structural information is absent for bZIP/bZIP+linker+LOV module. This study therefore aims for a thorough investigation of the bZIP domains from aureochromes and others, and their interaction with substrate DNA using tools from sequence/structural bioinformatics and network theory. With an in-depth comparison between 26 aureochrome subtypes and 147 plant/ophistokont bZIPs, we explore important residues at basic region and zipper - necessary for dimerization stability and DNA binding specificity. Perhaps the most notable finding is the unique histidine substitution at the DNA binding signature sequence of aureochromes, completely absent in any other bZIPs. Not only is this residue important for DNA binding, this can serve as a potential switch point in aureochrome/bZIP evolution. An all-atom network analysis on representative bZIP-DNA co-crystal structures, especially the measurement of eigenvector centrality, further adds importance to hydrophobic interactions in the zipper region to stabilize bZIP dimer and facilitate DNA binding.

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“…In respect to domain topology, aureochromes generally possess an N-terminal bZIP as an effector and C-terminal LOV as a sensor — yet aureochrome subtypes within an organism or from multiple organisms, execute diverse range of biological activities. This includes photomorphogenesis (Takahashi et al, 2007) (Deng et al, 2014), lipid accumulation (Huang et al, 2014), cell cycle progression (Mann et al, 2020), photo acclimation (Kroth et al, 2017) etc. Therefore, the fundamental question is despite structural identity, how such differences in activities ariseti There could be multiple possible factors including heterogeneity of linker connecting effector and sensor domain, uncharacterized N-terminal region of variable length and sequence, subtle differences in amino acid sequence composition of the sensor as well as effector that influences photoabsorption and leucine zipper dimerization/stability respectively.…”

Section: Introductionmentioning

confidence: 99%

“…In respect to domain topology, aureochromes generally possess an N-terminal bZIP as an effector and C-terminal LOV as a sensor -yet aureochrome subtypes within an organism or from mul?ple organisms, execute diverse range of biological ac?vi?es. This includes photomorphogenesis (Takahashi et al, 2007) (Deng et al, 2014), lipid accumula?on (Huang et al, 2014), cell cycle progression (Mann et al, 2020), photo acclima?on (Kroth et al, 2017) etc. Therefore, the fundamental ques?on is despite structural iden?ty, how such differences in ac?vi?es arise?…”

Section: Introductionmentioning

confidence: 99%

Assessing combinatorial diversity of aureochrome bZIPs through genome-wide screening

Khamaru

Nath

Mitra

et al. 2022

Preprint

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Aureochromes are unique blue light-responsive LOV (Light Oxygen Voltage) photoreceptors cum basic leucine zipper (bZIP) transcription factors (TFs), present exclusively in photosynthetic marine stramenopiles. Considering the availability of the complete genome sequence, this study focuses particularly on aureochromes from Ectocaupus siliculosus. Aureochromes mediate light-regulated developmental responses in this brown photosynthetic algae. Both the LOV sensor and the bZIP effector shows sequence-structure conservation. The LOV+bZIP modules of aureochrome homologs/paralogs are not only structurally similar but also show an identical oligomeric state -- preferably dimeric. Aureochromes execute diverse cellular responses in different photosynthetic stramenopiles -- though their activities can vary even within a given algal species. Besides a heterogeneous linker connecting the sensor-effector and a flexible N-terminal region, the sequence composition of both the domains is vital. Therefore, it is important to understand whether aureochromes select dimerization partners from the same family or interact with other bZIPs as well. To regulate multifarious biological activities, it is possible that aureochromes activate the global TF interaction network. Following homo/heterodimer modeling, we address the compatibility of dimerization partners by screening through heptad repeats. We evaluate the dimer interface area in terms of gain in solvation energy as well as the number of hydrogen bonds/salt bridge interactions. We further explore the relative stability of these structures from a graph-theoretic perspective through well-studied measures such as the energy of the graph and average participation coefficient. Furthermore, we also conduct an information-theoretic analysis using network information centrality and Kullback-Leibler divergence. We find that all our investigations into the relative stability of these dimers using diverse methods from bioinformatics, network science, and, information theory are in harmonious agreement. Our approach and findings should facilitate the design of experiments.

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The Aureochrome Photoreceptor PtAUREO1a Is a Highly Effective Blue Light Switch in Diatoms

Cited by 16 publications

References 67 publications

Potential for the Production of Carotenoids of Interest in the Polar Diatom Fragilariopsis cylindrus

Potential for the Production of Carotenoids of Interest in the Polar Diatom Fragilariopsis cylindrus

Basic Leucine Zippers: Aureochromes Versus the Rest

Assessing combinatorial diversity of aureochrome bZIPs through genome-wide screening

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