Biology subjects

Schoneberg, T.

Publications and source records attributed to Schoneberg, T..

4 recordsLinked to original sources

bioRxiv2023

Structural basis of GAIN domain autoproteolysis and cleavage-resistance in the adhesion G-protein coupled receptors

The GAIN domain is a hallmark of adhesion G-protein coupled receptors (aGPCRs) as this extracellular domain contains an integral agonistic sequence (Stachel) for activation via binding to the 7-transmembrane helical (7TM) domain of the receptor. Many aGPCRs are autoproteolytically cleaved at the GPCR proteolysis site (GPS) site within the GAIN domain formed HXS/T sequence motif. However, other aGPCR can be activated without GPS cleavage. We determined the crystal structure of the human ADGRB2/BAI2 hormone receptor (HormR) and GPCR autoproteolysis-inducing (GAIN) domains and found that this aGPCR is resistant to autoproteolysis despite the presence of a canonical HLS sequence motif at the GPS. We used structural comparisons and molecular dynamics (MD) simulations to identify structural determinants that are important for autocleavage beyond the canonical HXS/T motif. These studies characterized a conserved glycine residue and an edge-{pi} interaction of the histidine base of the GPS sequence with a phenylalanine residue that is highly conserved in cleavage-competent aGPCRs. The MD simulations showed that this interaction is important to position the imidazole group of the histidine for deprotonation of the serine or threonine nucleophile. Removal of this interaction reduced autoprote-olytic activity in the ADGRL1 receptor and restored cleavage competence of the ADGRB3 receptor in a R866H/L821F double mutant. Conservation analysis indicates that wild-type ADGRB2 and ADGRB3 are auto-cleavage-incompetent receptors.

biochemistry↗

bioRxiv2023

The N terminus-only (trans) function of the Adhesion GPCR Latrophilin-1 controls multiple processes in reproduction of C. elegans

Adhesion G protein-coupled receptors (aGPCR) are unique molecules. They are able to transmit classical signals via G-protein activation (7TM-dependent/cis signaling) as well as to mediate functions solely through their extracellular N termini, completely independent of the seven transmembrane helices domain (7TM) and the C terminus (7TM-independent/N terminus-only/trans function). This dual mode of action is highly unusual for GPCRs and allows for a plethora of possible cellular consequences. However, the physiological implications and molecular details of this N terminus-mediated signaling are not well understood. Here, we identify three distinct 7TM-independent/trans functions of the aGPCR Latrophilin homolog LAT-1 in the nematode Caenorhabditis elegans together regulating reproduction: sperm guidance, germline apoptosis and proliferative activity of germ cells in the gonadal stem cell niche. In these contexts, the receptor elicits its functions in a non-cell autonomous manner from adjacent somatic cells. These functions might be realized through alternative splicing of the receptor specifically generating N terminus-only variants. Thus, our findings shed light on the versatility of 7TM-independent/N terminus-only/trans functions of aGPCR and discusses possible molecular details.

physiology↗

bioRxiv2022

The dimerized pentraxin-like domain of the adhesion G protein-coupled receptor 112 (ADGRG4) suggests function in sensing mechanical forces

Adhesion G protein-coupled receptors (aGPCRs) feature large extracellular regions (ECRs) with modular domains that often resemble protein classes of various function. The pentraxin (PTX) domain, which is predicted by sequence homology within the ECR of four different aGPCR members, is well known to form pentamers and other oligomers. Oligomerization of GPCRs is frequently reported and mainly driven by interactions of the seven-transmembrane region and N- or C-termini. While the functional importance of dimers is well-established for some class C GPCRs, relatively little is known about aGPCR multimerization. Here, we showcase the example of ADGRG4, an orphan aGPCR that possesses a PTX-like domain at its very N-terminal tip, followed by an extremely long stalk containing serine-threonine repeats. Using x-ray crystallography and biophysical methods we determined the structure of this unusual PTX-like domain and provide experimental evidence for a homodimer equilibrium of this domain which is Ca2+-independent and driven by intermolecular contacts that differ vastly from the known soluble PTXs. The formation of this dimer seems to be conserved in mammalian ADGRG4 indicating functional relevance. Our data alongside of theoretical considerations lead to the hypothesis that ADGRG4 acts as an in vivo sensor for shear forces in enterochromaffin and Paneth cells of the small intestine.

biochemistry↗

bioRxiv2022

PTK7 is a positive allosteric modulator of GPR133 (ADGRD1) signaling in GBM

GPR133 (ADGRD1), an adhesion G protein-coupled receptor, supports growth of glioblastoma, a brain malignancy. We demonstrated that GPR133 is intramolecularly cleaved, and that dissociation of its N-terminal and C-terminal fragments (NTF and CTF) at the plasma membrane correlates with increased receptor signaling. However, how the extracellular interactome of GPR133 in glioblastoma modulates signaling remains unknown. Here, we use affinity purification and mass spectrometry to identify extracellular binding partners of GPR133 in patient-derived glioblastoma cells. We show that the transmembrane protein PTK7 binds the GPR133 NTF and its expression in trans increases GPR133 signaling. This effect requires the intramolecular cleavage of GPR133 and PTK7s anchoring in the plasma membrane. The GPR133-PTK7 interaction facilitates orthosteric activation of GPR133 by soluble peptide mimicking the endogenous tethered Stachel agonist, suggesting PTK7 binding allosterically enhances accessibility of GPR133s orthosteric Stachel binding pocket. GPR133 and PTK7 are expressed in adjacent cells in glioblastoma, where their knockdown phenocopies each other. We propose that this novel ligand-receptor interaction is relevant to the pathogenesis of glioblastoma, as well as physiological processes in several tissues.

cell biology↗