Biology subjects

Landfester, K.

Publications and source records attributed to Landfester, K..

5 recordsLinked to original sources

bioRxiv2026

A Phosphorylation-Induced Micellization switch in the low complexity domain of TDP-43

Abstract textPhase separation (PS) of the low-complexity domain (LCD) of TDP-43 is linked to pathogenic aggregates in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD-TDP). Here, we show that extensive phosphorylation of the LCD C-terminus redirects its self-assembly. Coarse-grained Monte Carlo simulations predicted that 12 Ser phosphorylations partition the 148-residue LCD into a hydrophobic N-terminal and highly charged C-terminal block, favoring finite-sized micellization over macroscopic PS. In vitro, LCD phosphorylated by casein kinase 1 delta (CK1{delta}; mean of 12 phosphorylations by native mass spectrometry) and phosphomimetic 12D/12DD mutants formed spherical nanoparticles ({approx} 20-50 nm) above a low-micromolar critical micelle concentration, whereas the unphosphorylated LCD underwent reversible PS that matured into fibrils. Increasing ionic strength shifted the mutants toward anisotropic morphologies (worm-like 12D micelles and rigid 12DD nanocylinders). Turbidity assays and confocal imaging directly visualized the absence of PS in the phosphorylated form. Negative-stain and cryo-EM confirmed the spherical micellar architecture for the phosphorylated LCD and 12D/12DD mimics. Our data identify phosphorylation as a molecular switch tuning macrophase separation and fibril formation of TDP-43 LCD, providing a framework for an aggregation-protective role through microphase separation into size-limited micelles. Whether these assemblies are stable or kinetically trapped on pathological timescales remains unclear.

biophysics↗

bioRxiv2025

Functional Mapping and Engineering of the Sec Translocon Unlocked by a Cell-Free System

Almost all proteins are inserted or translocated across membranes by the universally conserved Sec translocon. Despite its central role, experimental access to Sec function has remained limited. Here, we present a cell-free protein synthesis platform that inserts SecYEG into synthetic vesicles, enabling direct testing of Sec in real-time and high-throughput, circumventing longstanding viability constraints. Screening 300 Sec variants in a single experiment, we consolidate three decades of Sec research, while vastly expanding mutant diversity for structure-function insights. Mapping over 30 functionally critical regions that modulate Sec activity across three orders of magnitude, we uncover dozens of super-active variants. We further leverage our system to increase membrane protein quality and nanobody export, highlighting the potential of our system for advancing applications in synthetic biology and biotechnology.

molecular biology↗

bioRxiv2025

Structural basis of neurofibromin tetramerization and dimer-tetramer equilibrium

Human neurofibromin (NF1) is a tumor suppressor multidomain protein known to regulate cellular functions as a dimer. Using cryo-EM, we discovered that neurofibromin can form more highly organized structures and describe tetramerization and a dynamic dimer-to-tetramer equilibrium with extensive interlocked interfaces as well as structural flexibility. The new tetramer structure generates and modifies interaction surfaces and controls protein functions such as microtubule recruitment, thereby providing novel insights into cellular functions.

molecular biology↗

bioRxiv2021

Achieving dendritic cell subset-specific targeting in vivo by site-directed conjugation of targeting antibodies to nanocarriers

The major challenge of nanocarrier-based anti-cancer vaccination approaches is the targeted delivery of antigens and immunostimulatory agents to cells of interest, such as specific subtypes of dendritic cells (DCs), in order to induce robust antigen-specific anti-tumor responses. An undirected cell and body distribution of nanocarriers can lead to unwanted delivery to other immune cell types like macrophages reducing the vaccine efficacy. An often-used approach to overcome this issue is the surface functionalization of nanocarriers with targeting moieties, such as antibodies, mediating cell type-specific interaction. Numerous studies could successfully prove the targeting efficiency of antibody-conjugated carrier systems in vitro, however, most of them failed when targeting DCs in vivo that is partly due to cells of the reticuloendothelial system unspecifically clearing nanocarriers from the blood stream via Fc receptor ligation. Therefore, this study shows a surface functionalization strategy to site-specifically attach antibodies in an orientated direction onto the nanocarrier surface. Different DC-targeting antibodies, such as anti-CD11c, anti-CLEC9A, anti-DEC205 and anti-XCR1, were conjugated to the nanocarrier surface at their Fc domains. Anti-mouse CD11c antibody-conjugated nanocarriers specifically accumulated in the targeted organ (spleen) over time. Additionally, antibodies against CD11c and CLEC9A proved to specifically direct nanocarriers to the targeted DC subtype, conventional DCs type 1. In conclusion, site-directed antibody conjugation to nanocarriers is essential in order to avoid unspecific uptake by non-target cells while achieving antibody-specific targeting of DC subsets. This novel conjugation technique paves the way for the development of antibody-functionalized nanocarriers for DC-based vaccination approaches in the field of cancer immunotherapy.

bioengineering↗

bioRxiv2019

Biodegradable harmonophores for targeted high-resolution in vivo tumor imaging

Optical imaging probes have played a major role in detecting and monitoring of a variety of diseases1. In particular, nonlinear optical imaging probes, such as second harmonic generating (SHG) nanoprobes, hold great promise as clinical contrast agents, as they can be imaged with little background signal and unmatched long-term photostability2. As their chemical composition often includes transition metals, the use of inorganic SHG nanoprobes can raise long-term health concerns. Ideally, contrast agents for biomedical applications should be degraded in vivo without any long-term toxicological consequences to the organism. Here, we developed biodegradable harmonophores (bioharmonophores) that consist of polymer-encapsulated, self-assembling peptides that generate a strong SHG signal. When functionalized with tumor cell surface markers, these reporters can target single cancer cells with high detection sensitivity in zebrafish embryos in vivo. Thus, bioharmonophores will enable an innovative approach to cancer treatment using targeted high-resolution optical imaging for diagnostics and therapy.

bioengineering↗