9K75

SARS-CoV-2 related bat coronavirus BANAL-103 spike in the closed state

Summary for 9K75

• Entry DOI: 10.2210/pdb9k75/pdb
• Related: 9K6Z
• EMDB information: 62145
• Descriptor: Spike glycoprotein, 2-acetamido-2-deoxy-beta-D-glucopyranose (2 entities in total)
• Functional Keywords: sars-cov-2 related coronavirus, banal-103, spike, viral protein
• Biological source: Coronaviridae
• Total number of polymer chains: 3
• Total formula weight: 427157.17

Authors

Qingqing, L.,Xiao, C.,Xiaoning, L.,Yibing, Z.,Ru, L.,Zirui, K.,Didi, W.,Jiaxu, W.,Lili, L.,Junxia, Y.,Jianxiang, S.,Shuiling, J.,Ying, P.,Na, Z.,Yushun, W.,Jian, S. (deposition date: 2024-10-23, release date: 2025-07-16, Last modification date: 2025-09-10)

Primary citation

Li, Q.,Cai, X.,Li, X.,Zhang, Y.,Li, R.,Kang, Z.,Wan, D.,Wang, J.,Li, L.,Yang, J.,Shi, J.,Jin, S.,Sun, X.,Peng, Y.,Zang, N.,Xie, Z.,Wan, Y.,Shang, J.
Structural and functional constraints on spike activation and host protease utilization limit cell entry of SARS-CoV-2-related bat coronaviruses.
J.Virol., 99:e0100725-e0100725, 2025

PubMed Abstract: The persistent threat posed by SARS-CoV-2-related coronaviruses (SC2r-CoVs) in wildlife highlights the risk of zoonotic transmission. Cross-species infectivity is predominantly determined by spike (S) character and S-mediated cell entry. In this study, we systematically investigated BANAL-52 and BANAL-103, which exhibit the closest genetic proximity to SARS-CoV-2, focusing on their spike structures and functional characteristics. First, despite comparable receptor-binding domain (RBD)-ACE2 interactions, the spikes of BANAL-52 and BANAL-103 displayed significantly reduced ACE2 binding compared to SARS-CoV-2, suggesting impaired S activation. Second, Cryo-EM structural analyses revealed that BANAL-52 S is stabilized in a "locked" state through linoleic acid (LA) binding and an additional N370 glycan, whereas BANAL-103 S adopts a "closed" conformation due to a unique glycan network. Site-directed mutagenesis targeting the LA binding pocket confirmed that Y365 is related to S conformational transitions and viral entry. Third, both BANAL spikes relied predominantly on lysosomal proteases (e.g., cathepsins) for membrane fusion, unlike SARS-CoV-2, which utilizes a broader range of proteases (e.g., TMPRSS2 and furin). The introduction of a furin cleavage site enhanced the fusogenicity of BANAL spikes. Finally, sera from individuals who have recovered from SARS-CoV-2 effectively neutralized BANAL pseudoviruses, underscoring conserved antigenicity. Our findings elucidate structural and proteolytic barriers that restrict the zoonotic potential of these viruses and propose targeted surveillance strategies to preempt the emergence of SC2r-CoVs.

PubMed: 40704806
DOI: 10.1128/jvi.01007-25

Experimental method

ELECTRON MICROSCOPY (3.11 Å)