Biology subjects

Wurm, C. A.

Publications and source records attributed to Wurm, C. A..

2 recordsLinked to original sources

bioRxiv2021

Visualization of bacterial type 3 secretion system components down the molecular level by MINFLUX nanoscopy

Type 3 secretion systems (T3SS) are essential virulence factors of numerous bacterial pathogens and inject effector proteins into host cells. The needle-like T3SS machinery consists of more than 20 components, has a length of around 100 nm and a diameter of up to 30 nm according to EM studies. Its intrabacterial components are highly dynamic and in permanent exchange with other bacterial structures. Therefore, a temporally and spatially resolved visualization of the T3SS using fluorescence microscopy techniques has been challenging. In the present study, novel labeling strategies were combined with super-resolution microscopy such as STED, STORM and MINFLUX. MINFLUX nanoscopy allowed to visualize components of the T3SS machinery such as the dynamic sorting platform component YscL and the extrabacterial pore protein YopD at unprecedented resolutions. The presented results represent the basis for an in depth investigation of T3SS structure and function and therefore gain new insights into the infection process of human pathogens in order to develop novel treatment and prevention strategies.

microbiology↗

bioRxiv2021

Resolving the molecular architecture of the photoreceptor active zone by MINFLUX nanoscopy

Cells assemble macromolecular complexes into scaffoldings that serve as substrates for catalytic processes. Years of molecular neurobiology indicate that neurotransmission depends on such optimization strategies, yet the molecular topography of the presynaptic Active Zone (AZ) where transmitter is released upon synaptic vesicle (SV) fusion remains to be visualized. Therefore, we implemented MINFLUX optical nanoscopy to resolve the AZ of rod photoreceptors. To facilitate MINFLUX nanoscopy of the AZ, we developed and verified an immobilization technique, we name Heat Assisted Rapid Dehydration (HARD). Here fresh retinal slices are directly stamped onto glass coverslips yielding a single layer of rod AZs. These AZs exhibited excellent labeling efficiency and minimal signal redundancy in the Z-direction. Our data indicate that the SV release site is a molecular complex of bassoon-Rab3-binding molecule 2 (RIM2)-ubMunc13-2-CAST. The complexes are serially duplicated longitudinally, and reflected in register along the axis of symmetry of the synaptic ribbon. One sentence summaryStructural motifs formed by active zone proteins at the photoreceptor synapse.

neuroscience↗