Structural Basis for Recognition of a Gonococcal Lipooligosaccharide Epitope by Monoclonal Antibody 2C7 Informs Vaccine and Immunotherapeutic Design
4 affiliations
- 1University of Naples Federico II , , Via Cinthia 4 , , ,
- 2Michigan State University , , , ,
- 3University of Massachusetts Medical School , , , ,
- 4University of California San Francisco , , , ,
Abstract
Neisseria gonorrhoeae, the causative agent of gonorrhea, represents an escalating global health concern because of the rapid spread of antimicrobial resistance and the continued lack of an effective vaccine. The lipooligosaccharide (LOS) epitope targeted by monoclonal antibody 2C7 is highly conserved and expressed by the majority of clinical isolates, highlighting its potential as an attractive target for therapeutic and vaccine-based interventions. To define the molecular basis for 2C7 recognition, we structurally characterized mAb 2C7 bound to an LOS-derived octasaccharide. NMR and a 1.6 Å crystal structure of the Fab 2C7–octasaccharide complex showed that mAb 2C7 recognizes the β- and γ-glycan chains through an extensive network of hydrogen-bonding and hydrophobic interactions within the Fab binding cleft. MD simulations indicated that β and γ chains form stable, specific interactions with 2C7, whereas α-chain contacts are transient. Guided by structure, we synthesized a heptose II-linked β/γ-chain tetrasaccharide with its carrier-protein conjugate bound mAb 2C7 by ELISA and Western blotting. ITC revealed affinities comparable to the octasaccharide, confirming retention of key binding determinants. Binding was enthalpy-driven, consistent with crystallographic and MD-defined polar contacts. NMR confirmed engagement of all four residues, established as the minimal 2C7 epitope. These results provide a structural framework for the rational development of glycan-based vaccines and antibody therapeutics targeting antimicrobial-resistant N. gonorrhoeae.
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BibTeX
@article{tsagkarakou2026structural,
title = {{Structural Basis for Recognition of a Gonococcal Lipooligosaccharide Epitope by Monoclonal Antibody 2C7 Informs Vaccine and Immunotherapeutic Design}},
author = {Anastasia S. Tsagkarakou and Ferran Nieto-Fabregat and Alessandro Masi and Yunqin Zhang and Fei Fan and Jutamas Shaughnessy and Peter A. Rice and Xuefei Huang and Sanjay Ram and Peter T. Beernink and Alba Silipo},
journal = {JACS Au},
year = {2026},
month = oct,
doi = {10.1021/jacsau.6c01227},
url = {https://pubs.acs.org/jaaucr/article/doi/10.1021/jacsau.6c01227/5453780/Structural-Basis-for-Recognition-of-a-Gonococcal},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Structural Basis for Recognition of a Gonococcal Lipooligosaccharide Epitope by Monoclonal Antibody 2C7 Informs Vaccine and Immunotherapeutic Design
AU - Anastasia S. Tsagkarakou
AU - Ferran Nieto-Fabregat
AU - Alessandro Masi
AU - Yunqin Zhang
AU - Fei Fan
AU - Jutamas Shaughnessy
AU - Peter A. Rice
AU - Xuefei Huang
AU - Sanjay Ram
AU - Peter T. Beernink
AU - Alba Silipo
PY - 2026
DA - 2026/10/19
JO - JACS Au
DO - 10.1021/jacsau.6c01227
UR - https://pubs.acs.org/jaaucr/article/doi/10.1021/jacsau.6c01227/5453780/Structural-Basis-for-Recognition-of-a-Gonococcal
AB - Neisseria gonorrhoeae, the causative agent of gonorrhea, represents an escalating global health concern because of the rapid spread of antimicrobial resistance and the continued lack of an effective vaccine. The lipooligosaccharide (LOS) epitope targeted by monoclonal antibody 2C7 is highly conserved and expressed by the majority of clinical isolates, highlighting its potential as an attractive target for therapeutic and vaccine-based interventions. To define the molecular basis for 2C7 recognition, we structurally characterized mAb 2C7 bound to an LOS-derived octasaccharide. NMR and a 1.6 Å crystal structure of the Fab 2C7–octasaccharide complex showed that mAb 2C7 recognizes the β- and γ-glycan chains through an extensive network of hydrogen-bonding and hydrophobic interactions within the Fab binding cleft. MD simulations indicated that β and γ chains form stable, specific interactions with 2C7, whereas α-chain contacts are transient. Guided by structure, we synthesized a heptose II-linked β/γ-chain tetrasaccharide with its carrier-protein conjugate bound mAb 2C7 by ELISA and Western blotting. ITC revealed affinities comparable to the octasaccharide, confirming retention of key binding determinants. Binding was enthalpy-driven, consistent with crystallographic and MD-defined polar contacts. NMR confirmed engagement of all four residues, established as the minimal 2C7 epitope. These results provide a structural framework for the rational development of glycan-based vaccines and antibody therapeutics targeting antimicrobial-resistant N. gonorrhoeae.
SN - 2691-3704
ER -