Biology subjects

Breithaupt, C.

Publications and source records attributed to Breithaupt, C..

3 recordsLinked to original sources

bioRxiv2025

Strategies for Mitigating Radiation Damage and Improving Data Completeness in 3D Electron Diffraction of Protein Crystals

While 3D electron diffraction (3D-ED or microcrystal electron diffraction, MicroED) has emerged as a promising method for protein structure determination, its applicability is hindered by high susceptibility to radiation damage, leading to decreasing signal-to-noise ratio in consecutive diffraction patterns that limits the quality (resolution and redundancy) of the data. In addition, data completeness may be restricted due to the geometrical limitations of current sample holders and stages. In this work, we introduce an approach that addresses these issues using a commonly available 200keV cryo-electron microscope. The multi-position acquisition technique we present here combines (a) multiple data acquisitions from a single crystal over several tilt ranges and (b) merging data from a small number of crystals, each tilted about a different axis. The robustness of this approach is demonstrated by the de novo elucidation of a protein-peptide complex structure from only two orthorhombic microcrystals.

biochemistry↗

bioRxiv2024

Mechanism of SHP2 activation by bis-Tyr-phosphorylated Gab1

The non-receptor tyrosine phosphatase SHP2 (PTPN11) is a regulator of diverse cellular functions including mitogenic activation and cell migration. SHP2 consists of two tandem SH2 domains followed by the catalytic domain, and is autoinhibited by the N-terminal SH2 domain that blocks access to the active site. Mutations that influence auto-inhibition have been implicated in cancer and other diseases, and allosteric inhibitors have been developed that stabilise the inactive state. The mechanism of SHP2 activation remains unclear, however. Here, we show that the intrinsically disordered bis-phosphorylated SHP2-activating peptide pY627pY659-Gab1 binds to both SH2 domains, undergoing a partial disorder-to-order transition in the process. In addition to eliciting changes in SH2 domain dynamics, the peptide reorganises their relative orientations to provide a new SH2-SH2 interface. Our data suggest an active conformation for SHP2 that is also applicable to the hematopoietic cell-specific SHP1 (PTPN6), shedding light on the activation mechanism of both enzymes and paving the way for the development of novel compounds that modulate SHP2 activity.

biochemistry↗

bioRxiv2023

Self-assembly of Grb2 meshworks revealed by Grb2-Gab1497-528 complex structure

The ubiquitously expressed adaptor protein Growth factor receptor bound protein 2 (Grb2) plays an essential role in signal transduction by binding to activated receptor tyrosine kinases through its SH2 domain and to downstream effectors via its N- and C-terminal SH3 domains (nSH3, cSH3). Here we present the first structure of ligand-bound full length Grb2. The crystal structure of Grb2 in complex with a bidentate nSH3-cSH3-binding peptide, derived from the multi-site docking protein Grb2- associated binder-1 (Gab1), provides molecular insight into effector recognition by Grb2 and reveals the assembly of a two-dimensional meshwork, consisting of multimeric filament-like Grb2 chains linked to each other by the bivalent bound Gab1497-528 peptide. Dominant contacts between Grb2 molecules in the multimer are provided by an intermolecular SH2/cSH3 domain interface that is also present in the closed dimer of ligand-free Grb2. We further show that Grb2 is able to self-assemble to form phase-separated condensates in solution. The Grb2 SH2 domain phosphotyrosine binding site is freely accessible in the multimeric assembly, and phase separation is fostered by addition of Gab1497- 528, as expected from the crystal structure. Multimeric assembly is also observed using a Grb2 SH2- cSH3 didomain construct, and suppressed using a Grb2 Tyr60Glu mutant, a mimic of the in vivo phosphorylated Tyr160 central to the SH2/cSH3 interface, demonstrating that an intact SH2/cSH3 interface is needed for Grb2 assembly in solution.

biochemistry↗