Prof. Dr. Franz Bartl
Profil
Zusammenfassung
Franz Bartl erforscht die molekularen Mechanismen von Lichtrezeptoren, insbesondere wie Channelrhodopsine und Phytochrome Licht in biologische Signale umwandeln. Er nutzt zeitaufgelöste Spektroskopie-Methoden, um Protonentransferprozesse und strukturelle Veränderungen während der Photocyclen dieser Proteine zu verfolgen. Diese Expertise ist für die Optimierung von optogenetischen Werkzeugen und das Verständnis von Ionenkanalfunktion relevant.
Skills
Stammdaten
Identität, Organisation und Kontakt aus HU-FIS.
Forschungsthemen3
SFB 1078/2: Spektroskopische Untersuchungen von Protonentransferprozessen und wasserstoffgebundenen Netzwerken in Channelrhodopsinen und Phytochromen (TP B05)
Quelle ↗Förderer: DFG Sonderforschungsbereich Zeitraum: 04/2017 - 12/2020 Projektleitung: Prof. Dr. Franz Bartl
SFB 1078/3: Spektroskopische Untersuchungen von Protonentransferprozessen und wasserstoffgebundenen Netzwerken in Channelrhodopsinen und Phytochromen (TP B05)
Quelle ↗Förderer: DFG Sonderforschungsbereich Zeitraum: 01/2021 - 12/2024 Projektleitung: Prof. Dr. Franz Bartl
SFB 1078/3: Spektroskopische Untersuchungen von Protonentransferprozessen und wasserstoffgebundenen Netzwerken in Channelrhodopsinen und Phytochromen (TP B05)
Quelle ↗Förderer: DFG Sonderforschungsbereich Zeitraum: 01/2021 - 12/2024 Projektleitung: Prof. Dr. Franz Bartl
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Publikationen25
Top 25 nach Zitationen — Quelle: OpenAlex (BAAI/bge-m3 embedded für Matching).
Journal of Biological Chemistry · 192 Zitationen · DOI
Channelrhodopsin-2 (ChR2) is a microbial type rhodopsin and a light-gated cation channel that controls phototaxis in Chlamydomonas. We expressed ChR2 in COS-cells, purified it, and subsequently investigated this unusual photoreceptor by flash photolysis and UV-visible and Fourier transform infrared difference spectroscopy. Several transient photoproducts of the wild type ChR2 were identified, and their kinetics and molecular properties were compared with those of the ChR2 mutant E90Q. Based on the spectroscopic data we developed a model of the photocycle comprising six distinguishable intermediates. This photocycle shows similarities to the photocycle of the ChR2-related Channelrhodopsin of Volvox but also displays significant differences. We show that molecular changes include retinal isomerization, changes in hydrogen bonding of carboxylic acids, and large alterations of the protein backbone structure. These alterations are stronger than those observed in the photocycle of other microbial rhodopsins like bacteriorhodopsin and are related to those occurring in animal rhodopsins. UV-visible and Fourier transform infrared difference spectroscopy revealed two late intermediates with different time constants of tau = 6 and 40 s that exist during the recovery of the dark state. The carboxylic side chain of Glu(90) is involved in the slow transition. The molecular changes during the ChR2 photocycle are discussed with respect to other members of the rhodopsin family.
Nature Communications · 164 Zitationen · DOI
G-protein-coupled receptors (GPCRs) transmit extracellular signals to activate intracellular heterotrimeric G proteins (Gαβγ) and arrestins. For G protein signalling, the Gα C-terminus (GαCT) binds to a cytoplasmic crevice of the receptor that opens upon activation. A consensus motif is shared among GαCT from the Gi/Gt family and the ‘finger loop’ region (ArrFL1–4) of all four arrestins. Here we present a 2.75 Å crystal structure of ArrFL-1, a peptide analogue of the finger loop of rod photoreceptor arrestin, in complex with the prototypical GPCR rhodopsin. Functional binding of ArrFL to the receptor was confirmed by ultraviolet-visible absorption spectroscopy, competitive binding assays and Fourier transform infrared spectroscopy. For both GαCT and ArrFL, binding to the receptor crevice induces a similar reverse turn structure, although significant structural differences are seen at the rim of the binding crevice. Our results reflect both the common receptor-binding interface and the divergent biological functions of G proteins and arrestins. G-protein-coupled receptors (GPCRs) transmit signals through intracellular heterotrimeric G proteins and arrestins. Here, Szczepek et al.present the structure of a common binding interface for Gα and arrestin on rhodopsin to shed light on key interactions that mediate transduction of specific signals through a single GPCR.
Journal of Natural Products · 111 Zitationen · DOI
Hassallidin A (1), a new antifungal glycosylated lipopeptide, was isolated from an epilithic cyanobacterium collected in Bellano, Italy, identified as Tolypothrix (basionym Hassallia) species. Chemical, mass spectrometric, and spectroscopic analyses, including one- and two-dimensional NMR, were performed to determine an esterified eight-residue cyclic peptide linked with a carbohydrate and a fatty acid residue. Chiral GC-MS analysis revealed the occurrence of the nonproteinogenic amino acids D-allo-Thr, D-Thr, D-Tyr, D-Gln, and dehydroaminobutyric acid (Dhb) within the peptide moiety. The additional components of hassallidin A could be identified as alpha,beta-dihydroxytetradecanoic acid (Dht) and mannose. This is the first report on a cyclic peptide of cyanobacterial origin that contains both a fatty acid and a carbohydrate moiety. Compound 1 exhibits antifungal activity against Aspergillus fumigatus and Candida albicans with MIC values of 4.8 microg/mL for both test organisms.
Kooperationen1
Bestätigte Forscher↔Partner-Paare aus HU-FIS — Gold-Standard-Positive für das Matching.
SFB 1078/2: Spektroskopische Untersuchungen von Protonentransferprozessen und wasserstoffgebundenen Netzwerken in Channelrhodopsinen und Phytochromen (TP B05)
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