Lectin-like Intestinal Defensin Inhibits 2019-nCoV Spike binding to ACE2

Cheng Wang; Shaobo Wang; Daixi Li; Xia Zhao; Songling Han; Tao Wang; Gaomei Zhao; Yin Chen; Fang Chen; Jianqi Zhao; Liting Wang; Wei Sun; Yi Huang; Yongping Su; Dongqing Wei; Jinghong Zhao; Junping Wang

To gain an insight into the molecular interaction, we analyzed the recruitments of HD5 and HD6 to ACE2 by biolayer interferometry (BLI). The affinity of HD5 binding to recombinant human ACE2 immobilized on AR2G biosensors was 39.3 nM ( Figure 1A ), whereas no association signal was observed for HD6 ( Figure 1B) . The binding affinity of HD5 was much higher than that of a hexapeptide inhibitor, 438 YKYRYL 443 , derived from the RBD of SARS-CoV spike protein (46 μM) 27 . We previously discovered that HD5 is reduced to linear peptide, HD5 RED , under the catalysis of thioredoxin system in vivo 28, 29 . Interestingly, BLI revealed that similar to HD6, HD5 RED failed to bind ACE2 ( Figure 1C ). The structure-dependent interaction of HD5 with ACE2 is consistent with that cysteine replacement impairs the bactericidal and immunoregulatory efficiencies of HD5 30,31 , which expands the known roles of disulfide pairings in keeping the conformation of defensins.