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PRINCIPAL PUBLICATION AND AUTHORS

Mechanism of antibody-specific deglycosylation and immune evasion by Streptococcal IgG-specific endoglycosidases, B. Trastoy (a,b,c), J.J Du (d), J.O Cifuente (a,b), L. Rudolph (e), M. García-Alija (a,b), E.H. Klontz (f,g), D. Deredge (h), N. Sultana (d), C.G Huynh (d), M.W. Flowers (d), C. Li (i), D.E Sastre (d), L.-X. Wang (i), F. Corzana (j), A. Mallagaray (g), E.J. Sundberg (d), M.E. Guerin (a,b,c), Nat. Commun. 14, 1705 (2023); https:/doi.org/10.1038/s41467-023-37215-3 (a) Structural Glycobiology Laboratory, Biocruces Health Research Institute, Barakaldo (Spain) (b) Structural Glycobiology Laboratory, Center for Cooperative Research in Biosciences (CIC bioGUNE), Basque Research and Technology Alliance (BRTA), Derio (Spain) (c) Ikerbasque, Basque Foundation for Science, Bilbao (Spain) (d) Department of Biochemistry, Emory University School of Medicine, Atlanta (USA) (e) University of Lübeck, Center of Structural and Cell Biology in Medicine (CSCM), Institute of Chemistry and Metabolomics, Lübeck (Germany) (f) Department of Microbiology and Immunology, University of Maryland School of Medicine, Baltimore (USA) (g) Institute of Human Virology, University of Maryland School of Medicine, Baltimore (USA) (h) Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, Baltimore (USA) (i) Department of Chemistry and Biochemistry, University of Maryland (USA) (j) Departamento Química and Centro de Investigación en Síntesis Química, Universidad de La Rioja, Rioja (Spain)

REFERENCES

[1] B. Trastoy et al., Curr. Opin. Struct. Biol. 72, 248-259 (2022). [2] B. Trastoy et al., Nat. Commun. 9(1), 1874 (2018). [3] E.H. Klontz et al., ACS Cent. Sci. 5(3), 524-538 (2019). [4] B. Trastoy et al., Nat. Commun. 11, 899 (2020). [5] M. García-Alija et al., Biotechnology Adv. 67, 108201 (2023).

that the Fc region is located at the cleft of the V -shaped structure of the multi-modular EndoS, between the glycoside hydrolase (GH) and the β-sandwich domains. The EndoS GH domain interacts with the N-glycan and the CH2 domain of the Fc region. Strikingly, the β-sandwich domain of EndoS confers specificity through protein-protein interaction with the Fc region. EndoS- and EndoS2-mediated hydrolysis of the two glycans on Fc or IgG was shown to occur sequentially, concomitant with dissociation of the enzyme:substrate complex after hydrolysis of the first glycan before re-associating to hydrolyse the second glycan. Finally, it was determined that the sterically constrained glycan binding site of EndoS2 prevents deglycosylation of potential non-IgG glycoprotein substrates.

Altogether, the combined use of structural biology, in the form of cryo-EM, small-angle X-ray scattering, nuclear magnetic resonance and molecular dynamics analyses, extensive alanine scanning mutagenesis, hydrolytic activity and enzyme kinetics measurements allowed the determination of the molecular mechanisms of strict recognition and specificity by EndoS and EndoS2 for IgG antibodies. This is a timely and major finding that makes important contributions to the understanding of how IgG- specific immunomodulatory endoglycosidases promote immune evasion by a major human pathogenic bacteria. In addition, the study of the molecular mechanisms of substrate recognition of IgG1 by EndoS and EndoS2 is of critical importance to the design of novel strategies for the synthesis of monoclonal antibodies with improved therapeutic properties and the engineering of new enzymes to treat diseases of the adaptive immune system.