Biology subjects

Shahsavar, A.

Publications and source records attributed to Shahsavar, A..

2 recordsLinked to original sources

bioRxiv2021

The beryllium fluoride form of the Na+,K+-ATPase and the intermediates of the functional cycle

The Na+,K+-ATPase generates electrochemical gradients of Na+ and K+ across the plasma membrane. Here, we describe a 4.0 [A] resolution crystal structure of the pig kidney Na+,K+-ATPase stabilized by beryllium fluoride (denoted E2-BeFx). The structure shows high resemblance to the E2P phosphoenzyme obtained by phosphorylation from inorganic phosphate (Pi) and stabilised by cardiotonic steroids, and reveals a Mg2+ bound near the ion binding site II. Anomalous Fourier analysis of the crystals soaked in Rb+ (K+ congener) followed by a low resolution rigid-body refinement (6.9-7.5 [A]) revealed pre-occlusion transitions leading to activation of the desphosphorylation reaction. Mg2+ location indicates a site of an initial K+ recognition and acceptance upon binding to the outward-open E2P state after Na+ release. Despite the overall structural resemblance to the Pi-induced E2P phosphoform, BeFx inhibited enzyme is able to bind both ADP/ATP and ions - features that relate E2-BeFx complex to an intermediate of the functional cycle of the Na+,K+-ATPase prior E2P.

biochemistry↗

bioRxiv2020

Structural insights into glycine reuptake inhibition

The human glycine transporter 1 (GlyT1) regulates glycine mediated neuronal excitation and inhibition through sodium- and chloride-dependent reuptake of the neurotransmitter1-3. Inhibition of glycine reuptake via GlyT1 prolongs neurotransmitter signaling and has long served as a key therapeutic development strategy for treatment of a broad range of central nervous system disorders including schizophrenia and cognitive impairments4. Using an inhibition state-selective sybody and serial synchrotron crystallography, we determined the structure of GlyT1 in complex with a benzoylpiperazine chemotype inhibitor at 3.4 [A] resolution. The inhibitor locks GlyT1 in an inward-open conformation and binds at the intracellular gate of the release pathway, overlapping with the glycine release site. The inhibitor likely reaches GlyT1 from the cytoplasmic leaflet of the plasma membrane. The study defines the mechanism of non-competitive inhibition and enables the rational design of new, clinically efficacious GlyT1 inhibitors.

neuroscience↗