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Biology subjects

Heydenreich, F.

Publications and source records attributed to Heydenreich, F..

2 recordsLinked to original sources

Multiple triggers converge to preferential effector coupling in the CB2R through a complex allosteric communication network

G protein-coupled receptors are important therapeutic drug targets for a wide range of diseases. Their ability to preferentially engage specific signaling pathways over others can be exploited to design drugs that target only disease-associated pathways leading to an improved safety profile. However, the underlying molecular mechanisms for preferential pathway engagement are complex and remain largely elusive. To elucidate the multifaceted actions at the receptor level that lead to preferential coupling, we employ a combination of techniques. Our approach integrates systematic mutagenesis of the CB2R and comprehensive profiling of Gi2 and {beta}-arrestin1 engagements with computer simulations to track mutant-induced impacts on receptor dynamics. Most importantly, our research discloses multiple triggers on a complex allosteric communication network (ACN) that converge to preferential CB2R coupling by modulating evolutionary conserved motifs (e.g., CWxP, NPxxY, sodium binding site). Potent triggers for a preferential Gi2 response exhibit high levels of connectivity and are located in proximity to connections with high information transmission. Our insights highlight the complexity of GPCR signaling and can guide the rational design of drug candidates tailored to evoke specific functional responses that can enhance the precision and efficacy of therapeutic interventions.

cell biology↗

GlnK facilitates the dynamic regulation of bacterial nitrogen assimilation

Ammonium assimilation in E. coli is regulated by two paralogous proteins (GlnB and GlnK), which orchestrate interactions with regulators of gene expression, transport proteins and metabolic pathways. Yet how they conjointly modulate the activity of glutamine synthetase (GS), the key enzyme for nitrogen assimilation, is poorly understood. We combine experiments and theory to study the dynamic roles of GlnB and GlnK during nitrogen starvation and upshift. We measure time-resolved in vivo concentrations of metabolites, total and post-translationally modified proteins, and develop a concise biochemical model of GlnB and GlnK that incorporates competition for active and allosteric sites, as well as functional sequestration of GlnK. The model predicts the responses of GS, GlnB and GlnK under time-varying external ammonium level in the wild type and two genetic knock-outs. Our results show that GlnK is tightly regulated under nitrogen-rich conditions, yet it is expressed during ammonium run-out and starvation. This suggests a role for GlnK as a buffer of nitrogen shock after starvation, and provides a further functional link between nitrogen and carbon metabolisms.

systems biology↗