Biology subjects

Pieprzyk, J.

Publications and source records attributed to Pieprzyk, J..

2 recordsLinked to original sources

bioRxiv2021

Structural snapshots of human PepT1 and PepT2 reveal mechanistic insights into substrate and drug transport across epithelial membranes

The uptake of peptides in mammals plays a crucial role in nutrition and inflammatory diseases. This process is mediated by promiscuous transporters of the Solute Carrier Family 15, which form part of the Major Facilitator superfamily. Besides the uptake of short peptides, Peptide transporter 1 (PepT1) is a highly abundant drug transporter in the intestine and represents a major route for oral drug delivery. Peptide transporter 2 (PepT2) allows in addition renal drug reabsorption from ultrafiltration and brain-to-blood efflux of neurotoxic compounds. Here we present cryo-EM structures of human PepT1 in an outward open state and of human PepT2 in an inward facing partially occluded state with a bound substrate. The structures reveal the architecture of human peptide transporters and provide mechanistic insights into substrate recognition and conformational transitions during transport. Importantly, this may support future drug design efforts to increase the bioavailability of different drugs in the human body.

biophysics↗

bioRxiv2020

Selection, biophysical and structural analysis of synthetic nanobodies that effectively neutralize SARS-CoV-2

The coronavirus SARS-CoV-2 is the cause of the ongoing COVID-19 pandemic. Therapeutic neutralizing antibodies constitute a key short-to-medium term approach to tackle COVID-19. However, traditional antibody production is hampered by long development times and costly production. Here, we report the rapid isolation and characterization of nanobodies from a synthetic library, known as sybodies (Sb), that target the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. Several binders with low nanomolar affinities and efficient neutralization activity were identified of which Sb23 displayed high affinity and neutralized pseudovirus with an IC50 of 0.6 {micro}g/ml. A cryo-EM structure of the spike bound to Sb23 showed that Sb23 binds competitively in the ACE2 binding site. Furthermore, the cryo-EM reconstruction revealed a novel conformation of the spike where two RBDs are in the up ACE2-binding conformation. The combined approach represents an alternative, fast workflow to select binders with neutralizing activity against newly emerging viruses.

biophysics↗