Biology subjects

Meixner, A. J.

Publications and source records attributed to Meixner, A. J..

4 recordsLinked to original sources

bioRxiv2024

Simultaneous and Dynamic Super-Resolution Imaging of Two Proteins in Arabidopsis thaliana using dual-color sptPALM

Super-resolution microscopy techniques have revolutionized cell biology by providing insights into single-molecule dynamics and nanoscale organization within living cells. However, the application of dynamic live-cell methods in plants remains limited by the availability of suitable fluorophores for simultaneous visualization of multiple proteins. To address this challenge, we implemented a dual-color single-particle tracking photoactivated localization microscopy (sptPALM) approach based on codon-optimized photoactivatable fluorescent proteins PA-GFP and PATagRFP. Recently, we demonstrated their individual performance in single-color experiments in Nicotiana benthamiana and Arabidopsis thaliana cells. Here, we establish their combined use for dual-color sptPALM, enabling the simultaneous tracking of two distinct protein species within the same plant cell. This approach provides a framework to investigate the coordinated dynamics, interactions, and spatial organization of multiple proteins in living plant cells.

plant biology↗

bioRxiv2023

GreenMemTraX: A User-Friendly Software for Super-Resolution Analysis of Membrane Protein Dynamics and Nanoscale Organization in Plants

Super-resolution microscopy (SRM) approaches revolutionize cell biology by providing insights into the nanoscale organization and dynamics of macromolecular assemblies and single molecules in living cells. A major hurdle limiting SRM democratization is post-acquisition data analysis which is often complex and time-consuming. Here, we present OneFlowTraX, a user-friendly and open-source software dedicated to the analysis of single-molecule localization microscopy (SMLM) approaches such as single-particle tracking photoactivated localization microscopy (sptPALM). Through an intuitive graphical user interface, OneFlowTraX provides an automated all-in-one solution for single-molecule localization, tracking, as well as mobility and clustering analyses. OneFlowTraX allows the extraction of diffusion and clustering parameters of millions of molecules in a few minutes. Finally, OneFlowTraX greatly simplifies data management following the FAIR (Findable, Accessible, Interoperable, Reusable) principles. We provide a detailed step-by-step manual and guidelines to assess the quality of single-molecule analyses. Applying different fluorophores including mEos3.2, PA-GFP, and PATagRFP, we exemplarily used OneFlowTraX to analyze the dynamics of plant plasma membrane-localized proteins including an aquaporin, the brassinosteroid receptor Brassinosteroid Insensitive 1 (BRI1) and the Receptor-Like Protein 44 (RLP44).

plant biology↗

bioRxiv2019

Quantum coherence in the photosynthesis apparatus of living cyanobacteria

The first step in photosynthesis is an extremely efficient energy transfer mechanism, which is difficult to be explained by classical short-range energy migration ("hopping") and led to the debate to which extent quantum coherence is involved in the energy transfer between the photosynthetic pigments. Embedding living cyanobacteria between the mirrors of an optical microresonator and using low intensity white light irradiation we observe vacuum Rabi splitting in the transmission and fluorescence spectra as a result of strong light matter coupling of the chlorophyll and the resonator modes. The Rabi-splitting scales with the number of chlorophyll a pigments involved in coherent coupling indicating forming a polaritonic state which is delocalized over the entire cyanobacterial thylakoid system, down to the single photon level. Our data provide evidence that a delocalized polaritonic state is the basis of the extremely high energy transfer efficiency under natural conditions.

biophysics↗

bioRxiv2019

Three-fluorophore FRET-FLIM enables the study of trimeric protein interactions and complex formation with nanoscale resolution in living plant cells

Protein-protein interaction studies provide valuable insights into cellular signaling. The well-studied brassinosteroid (BR) signaling is initiated by the hormone-binding receptor Brassinosteroid Insensitive 1 (BRI1) and its co-receptor BRI1 Associated Kinase 1 (BAK1). BRI1 and BAK1 were shown to interact independently with the Receptor-Like Protein 44 (RLP44), which is implicated in BRI1/BAK1-dependent cell wall integrity perception. To demonstrate the proposed complex formation of BRI1, BAK1 and RLP44, we established three-fluorophore intensity-based spectral Forster resonance energy transfer (FRET) and FRET-fluorescence lifetime imaging microscopy (FLIM) for living plant cells. Our evidence indicates that RLP44, BRI1 and BAK1 form a ternary complex in a distinct plasma membrane nanodomain. In contrast, although the immune receptor Flagellin Sensing 2 (FLS2) also forms a heteromer with BAK1, the FLS2/BAK1 complexes are localized in other nanodomains. In general, our three-fluorophore FRET approaches provide a feasible basis for studying the interaction and sub-compartmentalization of proteins in great detail.

plant biology↗