Biology subjects

Stsiapanava, A.

Publications and source records attributed to Stsiapanava, A..

4 recordsLinked to original sources

bioRxiv2025

Uromodulin velcro sheets and their interaction with uropathogenic E. coli

Homopolymeric uromodulin (UMOD), the most abundant protein in human urine, protects against urinary tract infections (UTI) by acting as a decoy for uropathogenic E. coli (UPEC). Using cryo-electron tomography (ET), we show that urinary UMOD filaments naturally form sheets that interact with UPEC type I pili. Sheet formation is salt-dependent, and we resolve their high-resolution structure using single-particle cryo-electron microscopy (EM). This reveals a lateral interface between polymers, whose mutation disrupts UMOD filament bundle formation in mammalian cells. Branchless egg coat protein ZPD also forms sheets, and cryo-ET of elastase-treated UMOD indicates that absence of N-terminal branches promotes the stacking of UMOD-like protein sheets into thick 3D matrices. These results rationalize early observations of salt-dependent aggregation of UMOD, explain how UMOD can assemble into extended velcro-like structures that efficiently inactivate a multitude of adhesive UPEC pili, and suggest how UMOD-like molecules can generally organize into supramolecular structures of variable thickness.

biophysics↗

bioRxiv2025

Structural basis of ZP2-targeted immunocontraception

Monoclonal antibody IE-3 prevents mouse fertilization by binding ZP2, a major component of the oocyte-specific zona pellucida (ZP). We show that an IE3-derived single-chain variable fragment (scFV) is sufficient for blocking fertilization in vitro and determine the structural basis of IE-3/ZP2 recognition. The high-affinity of this interaction depends on induced fit of the epitope, offering insights for non-hormonal immunocontraceptive design without off-target effects.

biophysics↗

bioRxiv2023

Architecture of the Vertebrate Egg Coat and Structural Basis of the ZP2 Block to Polyspermy

Post-fertilization cleavage of glycoprotein ZP2, a major subunit of egg zona pellucida (ZP) filaments, is crucial for mammalian reproduction by irreversibly blocking polyspermy. ZP2 processing is thought to inactivate a sperm-binding activity located upstream of the proteins cleavage site; however, its molecular consequences and connection with ZP hardening are unknown. Here we report X-ray crystallographic, cryo-EM and biochemical studies showing that cleavage of ZP2 triggers its oligomerization. Deletion of the ZP-N1 domain that precedes the cleavage site of mouse ZP2 allows it to homodimerize even without processing, and animals homozygous for this variant are subfertile by having a semi-hardened ZP that allows sperm attachment but hinders penetration. Combined with the structure of a native egg coat filament, which reveals the molecular basis of heteromeric ZP subunit interaction, this suggests that oligomerization of cleaved ZP2 cross-links the ZP, rigidifying it and making it physically impenetrable to sperm.

biophysics↗

bioRxiv2020

Cryo-EM Structure of Native Human Uromodulin, a Zona Pellucida Module Polymer

Assembly of extracellular filaments and matrices mediating fundamental biological processes such as morphogenesis, hearing, fertilization and antibacterial defense is driven by a ubiquitous polymerization module known as zona pellucida (ZP) "domain". Despite the conservation of this element from hydra to human, no information is available on the filamentous conformation of any ZP module protein. Here we report the cryo-electron microscopy structure of uromodulin (UMOD)/Tamm-Horsfall protein, the most abundant protein in human urine and an archetypal ZP module-containing molecule, in its mature homopolymeric state. UMOD forms a one-start helix with an unprecedented 180-degree twist between subunits enfolded by interdomain linkers that have completely reorganized as a result of propeptide dissociation. Lateral interaction between filaments in the urine generates sheets exposing a checkerboard of binding sites to capture uropathogenic bacteria, and UMOD-based models of mammalian and avian heteromeric egg coat filaments identify a common sperm-binding region at the interface between subunits.

biophysics↗