The N-terminal region of the ubiquitin regulatory x (UBX) domain-containing Protein 1 (UBXD1) modulates interdomain communication within the valosin-containing Protein p97

Valosin-containing protein/p97 is an ATP-driven protein segregase that cooperates with distinct protein cofactors to control various aspects of cellular homeostasis. Mutations at the interface between the regulatory N-domain and the first of two ATPase domains (D1 and D2) deregulate the ATPase activity and cause a multisystem degenerative disorder, inclusion body myopathy associated with Paget disease of bone and frontotemporal dementia/amyotrophic lateral sclerosis. Intriguingly, the mutations affect only a subset of p97-mediated pathways correlating with unbalanced cofactor interactions and most prominently compromised binding of the ubiquitin regulatory X domain-containing protein 1 (UBXD1) cofactor during endolysosomal sorting of caveolin-1. However, how the mutations impinge on the p97-cofactor interplay is unclear so far. In cell-based endosomal localization studies, we identified a critical role of the N-terminal region of UBXD1 (UBXD1-N). Biophysical studies using NMR and CD spectroscopy revealed that UBXD1-N can be classified as intrinsically disordered. NMR titration experiments confirmed a valosin-containing protein/p97 interaction motif and identified a second binding site at helices 1 and 2 of UBXD1-N as binding interfaces for p97. In reverse titration experiments, we identified two distant epitopes on the p97 N-domain that include disease-associated residues and an additional interaction between UBXD1-N and the D1D2 barrel of p97 that was confirmed by fluorescence anisotropy. Functionally, binding of UBXD1-N to p97 led to a reduction of ATPase activity and partial protection from proteolysis. These findings indicate that UBXD1-N intercalates into the p97-ND1 interface, thereby modulating interdomain communication of p97 domains and its activity with relevance for disease pathogenesis. We propose that the polyvalent binding mode characterized for UBXD1-N is a more general principle that defines a subset of p97 cofactors

The de-ubiquitylating enzyme DUBA is essential for spermatogenesis in Drosophila

De-ubiquitylating enzymes (DUBs) reverse protein ubiquitylation and thereby control essential cellular functions. Screening for a DUB that counteracts caspase ubiquitylation to regulate cell survival, we identified the Drosophila ovarian tumour-type DUB DUBA (CG6091). DUBA physically interacts with the initiator caspase death regulator Nedd2-like caspase (Dronc) and de-ubiquitylates it, thereby contributing to efficient inhibitor of apoptosis-antagonist-induced apoptosis in the fly eye. Searching also for non-apoptotic functions of DUBA, we found that Duba-null mutants are male sterile and display defects in spermatid individualisation, a process that depends on non-apoptotic caspase activity. Spermatids of DUBA-deficient flies showed reduced caspase activity and lack critical structures of the individualisation process. Biochemical characterisation revealed an obligate activation step of DUBA by phosphorylation. With genetic rescue experiments we demonstrate that DUBA phosphorylation and catalytic activity are crucial in vivo for DUBA function in spermatogenesis. Our results demonstrate for the first time the importance of de-ubiquitylation for fly spermatogenesis

Macroscopic Displacement Reaction of Copper Sulfide in Lithium Solid-State Batteries

Copper sulfide (CuS) is an attractive electrode material for batteries, thanks to its intrinsic mixed conductivity, ductility and high theoretical specific capacity of 560 mAh g−1. Here, CuS is studied as cathode material in lithium solid-state batteries with an areal loading of 8.9 mg cm−2 that theoretically corresponds to 4.9 mAh cm−2. The configuration of the cell is LiLi3PS4[CuS (70 wt%) + Li3PS4 (30 wt%)]. No conductive additive is used. CuS undergoes a displacement reaction with lithium, leading to macroscopic phase separation between the discharge products Cu and Li2S. In particular, Cu forms a network of micrometer-sized, well-crystallized particles that seems to percolate through the electrode. The formed copper is visible to the naked eye. The initial specific discharge capacity at 0.1 C is 498 mAh g(CuS)−1, i.e., 84% of its theoretical value. The initial Coulomb efficiency (ICE) reaches 95%, which is higher compared to standard carbonate-based liquid electrolytes for the same cell chemistry (≈70%). After 100 cycles, the specific capacity reaches 310 mAh g(CuS)−1. With the current composition, the cell provides 58.2 Wh kg−1 at a power density of 7 W kg−1, which is superior compared to other transition metal sulfide cathodes.Peer Reviewe

Impaired iloprost-induced platelet inhibition and phosphoproteome changes in patients with confirmed pseudohypoparathyroidism type Ia, linked to genetic mutations in GNAS

Patients diagnosed with pseudohypoparathyroidism type Ia (PHP Ia) suffer from hormonal resistance and abnormal postural features, in a condition classified as Albright hereditary osteodystrophy (AHO) syndrome. This syndrome is linked to a maternally inherited mutation in the GNAS complex locus, encoding for the GTPase subunit Gs alpha. Here, we investigated how platelet phenotype and omics analysis can assist in the often difficult diagnosis. By coupling to the IP receptor, Gs alpha induces platelet inhibition via adenylyl cyclase and cAMP-dependent protein kinase A (PKA). In platelets from seven patients with suspected AHO, one of the largest cohorts examined, we studied the PKA-induced phenotypic changes. Five patients with a confirmed GNAS mutation, displayed impairments in Gs alpha -dependent VASP phosphorylation, aggregation, and microfluidic thrombus formation. Analysis of the platelet phosphoproteome revealed 2,516 phosphorylation sites, of which 453 were regulated by Gs alpha -PKA. Common changes in the patients were: (1) a joint panel of upregulated and downregulated phosphopeptides; (2) overall PKA dependency of the upregulated phosphopeptides; (3) links to key platelet function pathways. In one patient with GNAS mutation, diagnosed as non-AHO, the changes in platelet phosphoproteome were reversed. This combined approach thus revealed multiple phenotypic and molecular biomarkers to assist in the diagnosis of suspected PHP Ia.</p