Aug 2026· Toxicon· pp.
109273
· 0 citations· 54 references
Medicine
TL;DR
Although CD59 contains linear segments that recognize CB, this interaction is not sufficient to reproduce the PLA2-inhibitory function of CNF, suggesting that any functional interplay between these Ly6/uPAR proteins is likely to depend on more complex structural determinants.
Abstract
Structural motifs can be conserved among proteins with low primary-sequence identity, potentially supporting distinct yet related molecular functions. Endogenous phospholipase A2 inhibitors from snake plasma (sbPLIs) include the γ-type inhibitor from Crotalus durissus terrificus, known as Crotalus neutralizing factor (CNF), which protects the snake by selectively inhibiting the lethal and PLA2 activities of crotoxin (CTx). CD59, a complement regulator and single-LU-domain member of the Ly6/uPAR superfamily, shares the three-finger fold with CNF, raising the possibility of structural and functional convergence. Here, CD59 linear peptide arrays produced by SPOT synthesis were probed with CB, the PLA2 subunit of CTx, to identify CD59 regions capable of binding CB. Two reactive clusters were mapped, and derived peptides were synthesized and tested for their ability to inhibit the PLA2 activity of CTx and CB in vitro. Four CD59-derived peptides interacted with CB on the arrays; however, none inhibited PLA2 activity, in contrast to native CNF used as a positive control. These findings indicate that, although CD59 contains linear segments that recognize CB, this interaction is not sufficient to reproduce the PLA2-inhibitory function of CNF, suggesting that any functional interplay between these Ly6/uPAR proteins is likely to depend on more complex structural determinants.
Subcellular localization revealed that SsTFPI-1 predominantly localizes in the cytoplasm of EPC cells, and its C-terminus undergoes endogenous cleavage, which underscores the potential of TS20 as a promising antimicrobial agent.
Zhi-shu Zhu, Zi-yue Chen, Guang-hua Wang et al.· Fish and Shellfish Immunolog...· 0 citations
Simple Summary Porcine reproductive and respiratory syndrome virus (PRRSV) infection causes substantial economic losses to the global swine industry. PRRSV invades host target cells via receptor-mediated endocytosis, and CD163 is the most important receptor for PRRSV entry. Among the CD163 domains, the scavenger receptor cysteine-rich 5 (SRCR5) domain is essential for PRRSV infection. Therefore, CD163 and its SRCR5 are commonly selected as targets for developing anti-PRRSV strategies, including for the generation of CD163-SRCR5 knockout pigs. In addition, CD163 divergence also serves as a barrier to cross-species cellular infection by arteriviruses. Nevertheless, CD163 monoclonal antibodies (mAbs) with defined cross-species reactivity and anti-PRRSV activities have rarely been characterized. Here, we developed two mAbs against porcine CD163. Epitope mapping demonstrated that mAb 5A recognizes a novel epitope within the long loop 5-6 of the SRCR5 domain, while mAb 11D targets a conserved epitope within the SRCR4 domain. Functional validation revealed that mAb 5A can inhibit PRRSV infection, while mAb 11D cannot. Remarkably, mAb 11D exhibits broader cross-species reactivity than mAb 5A. Overall, this study provides a solid foundation for elucidating CD163-domain-dependent biological functions.
Yifan Meng, Shuai Yang, Jun Jiao et al.· Veterinary Sciences· 0 citations
The Hom family and canilysin are defined as helicolysins, a previously uncharacterized metzincin subfamily distinguished by a conserved Thr-turn and an accessory ND, and implicates these proteins in host-pathogen interactions, adhesion, and immunomodulation.
A. Rodríguez-Banqueri, T. Goulas, Marina Girbal-González et al.· Journal of Molecular Biology· 0 citations
This study explored cyclotide-based drug design against H5N1 using computational approaches and revealed that Psyle B and Psyle C exhibited strong interactions with HA and NA, highlighting Psyle B and Psyle C as promising antiviral leads.
S. Altaf, Kainat Sarwar, Rao Zahid Abbas et al.· Journal of Biomolecular Stru...· 0 citations
This study provides a new perspective for understanding the evolutionary conservation and species specificity of molluscan innate immune signaling pathways and offers important theoretical support for further comprehension of the molecular mechanism of scallop immune defense and promoting the green control of aquatic diseases in marine farming.
Xiaoxue Lin, Zihao Zhang, Xiaolong Chu et al.· Fish and Shellfish Immunolog...· 0 citations
In silico approaches are becoming increasingly important for enhancing the affinity of antibodies and antibody fragments, including single-chain variable fragments (scFvs). In this study, we present an in silico affinity-maturation workflow designed to improve the affinity of an scFv directed against
Neisseria meningitidis
factor H-binding protein (fHbp) by integrating in silico maturation, molecular dynamics (MD) simulations, and experimental validation. Approximately 300 single-point substitutions were designed at scFv residues predicted to interact with fHbp, and the resulting V3 (R99D) scFv–fHbp complexes were analyzed through all-atom MD simulations. Guided by bioinformatic analyses, the top V3 (R99D) variant was cloned and expressed, and its binding activity was validated by ELISA.
MD analyses identified five variants, Y35H, L31R, R99D, R99H, and A100K, that exhibited markedly enhanced complex stability. In all variants, the scFv secondary structure remained intact, whereas fHbp showed shrinkage relative to the scFv in the V3 (R99D)–fHbp complexes during the simulations. Hydrogen-bonding patterns and inter-residue distances further supported the improved affinity of the variants relative to the native form. The R99D variant showed the highest binding affinity, with an experimentally measured value of 67.93 × 10⁹ M⁻¹.
Collectively, these findings underscore affinity maturation as a powerful strategy for engineering high-affinity antibody fragments.
Bijan Ghazanfari, Zahra Ebrahimi, F. Yarian et al.· BMC Biotechnology· 0 citations