Mayumi Nagano

Publications (3)10.69 Total impact

• Article: A (13)C-detection NMR approach for large glycoproteins.

  Yoshiki Yamaguchi, Markus Wälchli, Mayumi Nagano, Koichi Kato
  [show abstract] [hide abstract]
  ABSTRACT: NMR spectroscopy has great potential to provide us with information on structure and dynamics at atomic resolution of glycoproteins in solution. In larger glycoproteins, however, the detrimental fast (1)H transverse relaxation renders the conventional (1)H-detected NMR experiments difficult. (13)C direct detection potentially offers a valuable alternative to (1)H detection to overcome the fast T(2) relaxation. Here, we applied (13)C-detected NMR methods to observe the NMR signals of (13)C-labeled glycans attached to the Fc fragment of immunoglobulin G with a molecular mass of 56kDa. Spectral analysis revealed that a (13)C-detected (13)C-(13)C NOESY experiment is highly useful for spectral assignments of the glycans of large glycoproteins. This approach would be, in part, complementary to (13)C-(13)C TOCSY and (1)H-detection experiments.
  Carbohydrate research 01/2009; 344(4):535-8. · 2.03 Impact Factor
• Source

  Available from: Koichi Kato

  Article: Structural comparison of fucosylated and nonfucosylated Fc fragments of human immunoglobulin G1.

  Shigeki Matsumiya, Yoshiki Yamaguchi, Jun-ichi Saito, Mayumi Nagano, Hiroaki Sasakawa, Shizuo Otaki, Mitsuo Satoh, Kenya Shitara, Koichi Kato
  [show abstract] [hide abstract]
  ABSTRACT: Removal of the fucose residue from the oligosaccharides attached to Asn297 of human immunoglobulin G1 (IgG1) results in a significant enhancement of antibody-dependent cellular cytotoxicity (ADCC) via improved IgG1 binding to Fcgamma receptor IIIa. To provide structural insight into the mechanisms of affinity enhancement, we determined the crystal structure of the nonfucosylated Fc fragment and compared it with that of fucosylated Fc. The overall conformations of the fucosylated and nonfucosylated Fc fragments were similar except for hydration mode around Tyr296. Stable-isotope-assisted NMR analyses confirmed the similarity of the overall structures between fucosylated and nonfucosylated Fc fragments in solution. These data suggest that the glycoform-dependent ADCC enhancement is attributed to a subtle conformational alteration in a limited region of IgG1-Fc. Furthermore, the electron density maps revealed that the traces between Asp280 and Asn297 of our fucosylated and nonfucosylated Fc crystals were both different from that in previously reported isomorphous Fc crystals.
  Journal of Molecular Biology 06/2007; 368(3):767-79. · 4.00 Impact Factor
• Article: Glycoform-dependent conformational alteration of the Fc region of human immunoglobulin G1 as revealed by NMR spectroscopy.

  Yoshiki Yamaguchi, Mamiko Nishimura, Mayumi Nagano, Hirokazu Yagi, Hiroaki Sasakawa, Kazuhisa Uchida, Kenya Shitara, Koichi Kato
  [show abstract] [hide abstract]
  ABSTRACT: The Fc portion of immunoglobulin G (IgG) expresses the biantennary complex type oligosaccharides at Asn297 of the C(H)2 domain of each heavy chain with microheterogeneities depending on physiological and pathological states. These N-glycans are known to be essential for promotion of proper effector functions of IgG such as complement activation and Fcgamma receptor (FcgammaR)-mediated activities. To gain a better understanding of the role of Fc glycosylation, we prepared a series of truncated glycoforms of human IgG1-Fc and analyzed their interactions with human soluble FcgammaRIIIa (sFcgammaRIIIa) and with staphylococcal protein A by surface plasmon resonance and nuclear magnetic resonance (NMR) methods. Progressive but less pronounced reductions in the affinity for sFcgammaRIIIa were observed as a result of the galactosidase and subsequent N-acetylhexosaminidase treatments of IgG1-Fc. The following endoglycosidase D treatment, giving rise to a disaccharide structure composed of a fucosylated GlcNAc, abrogated the affinity of IgG1-Fc for sFcgammaRIIIa. On the other hand, those glycosidase treatments did not significantly affect the affinity of IgG1-Fc for protein A. Inspection of stable-isotope-assisted NMR data of a series of Fc glycoforms indicates that the stepwise trimming out of the carbohydrate residues results in concomitant increase in the number of amino acid residues perturbed thereby in the C(H)2 domains. Furthermore, the cleavage at the GlcNAcbeta1-4GlcNAc glycosidic linkage induced the conformational alterations of part of the lower hinge region, which makes no direct contact with the carbohydrate moieties and forms the major FcgammaR-binding site, while the conformation of the C(H)2/C(H)3 interface was barely perturbed that is the protein A-binding site. These results indicate that the carbohydrate moieties are required for maintaining the structural integrity of the FcgammaR-binding site.
  Biochimica et Biophysica Acta 05/2006; 1760(4):693-700. · 4.66 Impact Factor