8W5R

Cryo-EM structure of Qb-Ab53

Summary for 8W5R

• Entry DOI: 10.2210/pdb8w5r/pdb
• EMDB information: 37302
• Descriptor: Minor capsid protein A1, Heavy chain of Ab53, Light chain of Ab53 (3 entities in total)
• Functional Keywords: qb, antibody, cryo-em, immune system
• Biological source: Escherichia phage Qbeta; More
• Total number of polymer chains: 5
• Total formula weight: 68872.18

Authors

Bao, K.Y.,Li, R.H.,Hua, Z.L.,Hou, B.D.,Zhu, P. (deposition date: 2023-08-27, release date: 2025-02-26)

Primary citation

Li, R.,Bao, K.,Liu, C.,Ma, X.,Hua, Z.,Zhu, P.,Hou, B.
Competition propels, rather than limits, the success of low-affinity B cells in the germinal center response.
Cell Rep, 44:115334-115334, 2025

PubMed Abstract: The germinal center (GC) sets an environment where antigen-specific B cells are compelled to continuously increase their affinity to compete for the antigen and obtain Tfh help for survival and propagation. Previous studies indicated that low-affinity B cells are disadvantaged in the presence of high-affinity ones, suggesting that competition may lead to the elimination of low-affinity B cells and their descendants. However, using a multivalent virus-mimicking antigen, our study demonstrates that low-affinity B cells not only successfully participate in GC responses alongside high-affinity B cells but also undergo accelerated affinity maturation under the more stringent competition. Furthermore, our cryo-electron-microscopy-based structural analysis reveals that both low-affinity and high-affinity B cells compete for the same antigenic epitope. Although the applicability of this idealized GC competition to true pathogen-induced responses remains uncertain, this change in perspective on the role of competition in low-affinity B cell evolution provides valuable insights for vaccine development.

PubMed: 39955776
DOI: 10.1016/j.celrep.2025.115334

Experimental method

ELECTRON MICROSCOPY (3.1 Å)