Denecke, J. | Search bioRxiv

bioRxiv2024

The two crystal structures of unloaded and cargo-loaded Vacuolar Sorting Receptor 1 lumenal domain (VSR1-Nt) reveal two cargo binding sites and a mechanism of transport.

Vacuolar sorting receptors (VSRs) are type I membrane proteins crucial for seed germination and plant development. While VSR trafficking has been extensively studied, the mechanism of cargo binding and release by the N-terminal lumenal region is less understood. We have elucidated the crystal structures of unloaded and cargo-loaded forms of the lumenal region of VSR1 containing the protease-associated domain, the Central domain and epidermal growth factor-like repeats. Calcium coordination induces remodeling of the linkers between domains, triggering large conformational changes that expose two binding sites, one across the PA and Central domain and a second site in the Central domain. Our findings provide a mechanistic model for cargo binding in a calcium rich environment, where VSR is locked in a conformation exposing the cargo binding sites, while cargo release is favoured by lower calcium concentrations and trimer formation. These results advance our current knowledge on VSRs and will inform future studies on vacuolar trafficking and cargo binding/release.

plant biology↗

bioRxiv2017

Survival Beyond the Perinatal Period Expands the Phenotypes Caused by Mutations in GLE1

Mutations in GLE1 underlie Lethal Congenital Contracture syndrome (LCCS1) and Lethal Arthrogryposis with Anterior Horn Cell Disease (LAAHD). Both LCCS1 and LAAHD are characterized by reduced fetal movements, congenital contractures, and a severe form of motor neuron disease that results in fetal death or death in the perinatal period, respectively. Via trio-exome sequencing, we identified bi-allelic mutations in GLE1 in two unrelated individuals with motor delays, feeding difficulties and respiratory insufficiency who survived beyond the perinatal period. Each affected child had missense variants predicted to result in amino acid substitutions near the C-terminus of GLE1 that are predicted to disrupt protein-protein interaction or GLE1 protein targeting. We hypothesize that mutations that preserve function of the coiled-coil domain of GLE1 cause LAAHD whereas mutations that abolish the function of the coiled-coil domain cause LCCS1. The phenotype of LAAHD is now expanded to include multiple individuals surviving into childhood suggesting that LAAHD is a misnomer and should be re-named Arthrogryposis with Anterior Horn Cell Disease (AAHD). Too few cases have been reported to identify significant genotype-phenotype relationships, but given that perinatal lethality in AAHD typically resulted from respiratory failure, it is possible that early or aggressive airway management such as early tracheostomy and ventilation may enable survival beyond the perinatal period.

genetics↗