Biology subjects

Metcalfe, R. D.

Publications and source records attributed to Metcalfe, R. D..

3 recordsLinked to original sources

bioRxiv2022

Structure and regulation of full-length human leucine-rich repeat kinase 1

The two human leucine-rich repeat kinases (LRRKs), LRRK1 and LRRK2 are large and unusually complex multi-domain kinases which serve to regulate fundamental cellular processes, with both implicated in human disease. Despite recent experimentally determined structures of LRRK2, the structure and exact molecular mechanisms regulating the activity of the LRRK1, and differences in the regulation of LRRK1 and LRRK2 remain unclear. Here, we report a cryo-EM structure of the LRRK1 monomer, and a lower-resolution cryo-EM map of the LRRK1 dimer. The monomer structure, in which the kinase is in an inactive conformation, reveals key interdomain interfaces which serve to control kinase activity, which are further validated experimentally. Both the LRRK1 monomer and dimer are structurally distinct compared to LRRK2, implying functional differences in both proteins. Overall, our results provide new structural insights into the activation of the human LRRKs for understanding the physiology and pathology of these proteins.

molecular biology↗

bioRxiv2022

Structures of the interleukin 11 signalling complex reveal dynamics of gp130 extracellular domains and the inhibitory mechanism of a cytokine variant

Interleukin (IL-)11, an IL-6 family cytokine, has pivotal roles in numerous autoimmune diseases, fibrotic complications, and solid cancers. Despite intense therapeutic targeting efforts, structural understanding of IL-11 signalling and mechanistic insights into current inhibitors is lacking. Here we present cryo-EM and crystal structures of the IL-11 signalling complex, including the complex containing the complete extracellular domains of the shared IL-6 family {beta}-receptor, gp130. We show that the membrane-proximal domains of gp130 are dynamic and do not participate in complex assembly. We demonstrate that the cytokine mutant IL-11 Mutein competitively inhibits signalling in human cell lines. Structural shifts in IL-11 Mutein underlie inhibitory activity by altering cytokine binding interactions at all three receptor-engaging sites and abrogating the final gp130 binding step. Our results reveal the structural basis of IL-11 signalling, define the molecular mechanisms of an inhibitor, and advance understanding of gp130-containing receptor complexes, with potential applications in therapeutic development.

cell biology↗

bioRxiv2021

Structural insights into the modes of relaxin-binding and tethered-agonist activation of RXFP1 and RXFP2

Our poor understanding of the mechanism by which the peptide-hormone H2 relaxin activates its G protein coupled receptor, RXFP1 and the related receptor RXFP2, has hindered progress in its therapeutic development. Both receptors possess large ectodomains, which bind H2 relaxin, and contain an N-terminal LDLa module that is essential for receptor signalling and postulated to be a tethered agonist. Here, we show that a conserved motif (GDxxGWxxxF), C-terminal to the LDLa, is critical for receptor activity. Importantly, this motif adopts different structures in RXFP1 and RXFP2, suggesting distinct activation mechanisms. For RXFP1, the motif is flexible, weakly associates with the LDLa, and requires H2 relaxin binding to stabilize an active conformation. Conversely, the GDxxGWxxxF motif in RXFP2 is more closely associated with the LDLa, forming an essential binding interface for H2 relaxin. These differences in the activation mechanism will aid drug development targeting these receptors.

biophysics↗