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- Carrillo, M., et al.
(författare)
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High-resolution crystal structures of transient intermediates in the phytochrome photocycle
- 2021
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Ingår i: Structure. - : Elsevier BV. - 0969-2126. ; 29:7, s. 743-
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Tidskriftsartikel (refereegranskat)abstract
- Phytochromes are red/far-red light photoreceptors in bacteria to plants, which elicit a variety of important physiological responses. They display a reversible photocycle between the resting Pr state and the light-activated Pfr state. Light signals are transduced as structural change through the entire protein to modulate its activity. It is unknown how the Pr-to-Pfr interconversion occurs, as the structure of intermediates remains notoriously elusive. Here, we present short-lived crystal structures of the photosensory core modules of the bacteriophytochrome from myxobacterium Stigmatella aurantiaca captured by an X-ray free electron laser 5 ns and 33 ms after light illumination of the Pr state. We observe large structural displacements of the covalently bound bilin chromophore, which trigger a bifurcated signaling pathway that extends through the entire protein. The snapshots show with atomic precision how the signal progresses from the chromophore, explaining how plants, bacteria, and fungi sense red light.
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| 3. |
- Sanchez, J. C., et al.
(författare)
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High-resolution crystal structures of amyxobacterial phytochrome at cryo and roomtemperatures
- 2019
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Ingår i: Structural Dynamics-Us. - : AIP Publishing. - 2329-7778. ; 6:5
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Tidskriftsartikel (refereegranskat)abstract
- Phytochromes (PHYs) are photoreceptor proteins first discovered in plants, where they control a variety of photomorphogenesis events. PHYs as photochromic proteins can reversibly switch between two distinct states: a red light (Pr) and a far-red light (Pfr) absorbing form. The discovery of Bacteriophytochromes (BphPs) in nonphotosynthetic bacteria has opened new frontiers in our understanding of the mechanisms by which these natural photoswitches can control single cell development, although the role of BphPs in vivo remains largely unknown. BphPs are dimeric proteins that consist of a photosensory core module (PCM) and an enzymatic domain, often a histidine kinase. The PCM is composed of three domains (PAS, GAF, and PHY). It holds a covalently bound open-chain tetrapyrrole (biliverdin, BV) chromophore. Upon absorption of light, the double bond between BV rings C and D isomerizes and reversibly switches the protein between Pr and Pfr states. We report crystal structures of the wild-type and mutant (His275Thr) forms of the canonical BphP from the nonphotosynthetic myxobacterium Stigmatella aurantiaca (SaBphP2) in the Pr state. Structures were determined at 1.65A degrees and 2.2A degrees (respectively), the highest resolution of any PCM construct to date. We also report the room temperature wild-type structure of the same protein determined at 2.1A degrees at the SPring-8 Angstrom Compact free electron LAser (SACLA), Japan. Our results not only highlight and confirm important amino acids near the chromophore that play a role in Pr-Pfr photoconversion but also describe the signal transduction into the PHY domain which moves across tens of angstroms after the light stimulus. (C) 2019 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
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- Castiglione, Alessandro, et al.
(författare)
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Docosahexaenoic acid normalizes QT interval in long QT type 2 transgenic rabbit models in a genotype-specific fashion
- 2022
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Ingår i: Europace. - : OXFORD UNIV PRESS. - 1099-5129 .- 1532-2092. ; 24:3, s. 511-522
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Tidskriftsartikel (refereegranskat)abstract
- Aim Long QT syndrome (LQTS) is a cardiac channelopathy predisposing to ventricular arrhythmias and sudden cardiac death. Since current therapies often fail to prevent arrhythmic events in certain LQTS subtypes, new therapeutic strategies are needed. Docosahexaenoic acid (DHA) is a polyunsaturated fatty acid, which enhances the repolarizing I-Ks current. Methods and results We investigated the effects of DHA in wild type (WT) and transgenic long QT Type 1 (LQT1; loss of I-Ks), LQT2 (loss of I-Kr), LQT5 (reduction of I-Ks), and LQT2-5 (loss of I-Kr and reduction of I-Ks) rabbits. In vivo ECGs were recorded at baseline and after 10 mu M/kg DHA to assess changes in heart-rate corrected QT (QTc) and short-term variability of QT (STVQT). Ex vivo monophasic action potentials were recorded in Langendorff-perfused rabbit hearts, and action potential duration (APD(75)) and triangulation were assessed. Docosahexaenoic acid significantly shortened QTc in vivo only in WT and LQT2 rabbits, in which both alpha- and beta-subunits of I-K(s)-conducting channels are functionally intact. In LQT2, this led to a normalization of QTc and of its short-term variability. Docosahexaenoic acid had no effect on QTc in LQT1, LQT5, and LQT2-5. Similarly, ex vivo, DHA shortened APD(75) in WT and normalized it in LQT2, and additionally decreased AP triangulation in LQT2. Conclusions Docosahexaenoic acid exerts a genotype-specific beneficial shortening/normalizing effect on QTc and APD(75) and reduces pro-arrhythmia markers STVQT and AP triangulation through activation of I-Ks in LQT2 rabbits but has no effects if either alpha- or beta-subunits to I-Ks are functionally impaired. Docosahexaenoic acid could represent a new genotype-specific therapy in LQT2.
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