Determination of specific and non-specific protein-protein interactions for beta-lactoglobulin by analytical ultracentrifugation and membrane osmometry experiments. | LitMetric
Protein-protein interactions are essential for the understanding of biological processes. Specific protein aggregation is an important aspect for many biological systems. In particular, electrostatic interactions play the key role for protein-protein interactions, as many amino acids have pH-dependent charge states. Moreover, protein dissociation is directly related to the solution pH, ionic strength, temperature and protein concentration. The subtle interplay between different specific and non-specific interactions is demonstrated for beta-lactoglobulin (BLG) with a focus on low salt concentrations, thus mimicking technically relevant processing conditions. BLG is a well-characterized model system, proven to attain its monomer-dimer equilibrium strongly dependent upon the pH of the solution. In this manuscript, we present a unique combination of analytical ultracentrifugation and membrane osmometry experiments, which quantifies specific and non-specific interactions, in terms of the dimer dissociation constants and the second osmotic virial coefficient, at pH 3 and 7 and sodium chloride concentrations of 10 mM and 100 mM. This provides direct insight to protein-protein interactions for a system with a concentration-dependent monomer-dimer equilibrium. Moreover, using a coarse-grained extended DLVO model in combination with molecular dynamics simulations, we quantify non-specific monomer-monomer, monomer-dimer and dimer-dimer interactions as well as the binding free energy of BLG dimerization from theoretical calculations. The experimentally determined interactions are shown to be mainly governed by electrostatic interactions and further agree with free energy calculations. Our experimental protocol aims to determine non-specific and specific interactions for a dynamically interacting system and provides an understanding of protein-protein interactions for BLG at low salt concentrations.
E3 ubiquitin ligases have been linked to developmental diseases including autism, Angelman syndrome (UBE3A), and Johanson-Blizzard syndrome (JBS) (UBR1). Here, we report variants in the E3 ligase UBR5 in 29 individuals presenting with a neurodevelopmental syndrome that includes developmental delay, autism, intellectual disability, epilepsy, movement disorders, and/or genital anomalies. Their phenotype is distinct from JBS due to the absence of exocrine pancreatic insufficiency and the presence of autism, epilepsy, and, in some probands, a movement disorder.
GABAergic synaptic inhibition controls circuit function by regulating neuronal plasticity, excitability, and firing. To achieve these goals, inhibitory synapses themselves undergo several forms of plasticity via diverse mechanisms, strengthening and weakening phasic inhibition in response to numerous activity-induced stimuli. These mechanisms include changing the number and arrangement of functional GABARs within the inhibitory postsynaptic domain (iPSD), which can profoundly regulate inhibitory synapse strength.
State Key Laboratory of Animal Biotech Breeding, Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing 100193, China. Electronic address:
Spermatozoa cryopreservation has been widely used for animal genetic conservation. Despite advances in chicken semen cryopreservation, the mechanism of spermatozoa cryodamage remains to be revealed. The cryopreservation process induces motion parameter decreased, structure damaged, proteomic and antioxidant system remodeled in spermatozoa.
Protein-protein interactions are often mediated by a modular peptide recognition domain binding to a short linear motif (SLiM) in the disordered region of another protein. To understand the features of SLiMs that are important for binding and to identify motif instances that are important for biological function, it is useful to examine the evolutionary conservation of motifs across homologous proteins. However, the intrinsically disordered regions (IDRs) in which SLiMs reside evolve rapidly.
