Id |
Subject |
Object |
Predicate |
Lexical cue |
T382 |
0-4 |
Sentence |
denotes |
6.2. |
T383 |
5-98 |
Sentence |
denotes |
SARS-CoV-2 Recognizes 9-O-Acetyl-SAs and MERS-CoV Recognizes α2,3-SAs as Attachment Receptors |
T384 |
99-167 |
Sentence |
denotes |
The S glycoprotein SARS-CoV-2 initiates infection of the host cells. |
T385 |
168-390 |
Sentence |
denotes |
The molecular basis of CoV attachment to sugar/glycan receptors is an important issue, as demonstrated by recent cryo-EM defining the structure of the CoV-OC43 S glycoprotein trimer complexed with a 9-O-acetylated SA [56]. |
T386 |
391-613 |
Sentence |
denotes |
Cryo-EM structures of the trimeric ectodomain of S glycoprotein were observed using forms complexed with Neu5Ac, Neu5Gc, sialyl–LewisX (SLeX), α2,3-sialyl-N-acetyl-lactosamine (α2,3-SLacNAc) and α2,6-SLacNAc, respectively. |
T387 |
614-867 |
Sentence |
denotes |
The receptor-binding site is commonly conserved in all CoV S glycoproteins, which attach to 9-O-Ac-SA species with similar ligand-binding pockets to the CoV HEs and influenza virus C/D HEF glycoproteins, indicating conserved recognizing structures [25]. |
T388 |
868-1009 |
Sentence |
denotes |
The S glycoprotein-9-O-acetyl-SA interaction resembles the ligand-binding pockets of CoV HEs and influenza virus C/D HE fusion glycoproteins. |
T389 |
1010-1049 |
Sentence |
denotes |
HCoV-OC43 and BCoV recognize 9-O-Ac-SA. |
T390 |
1050-1088 |
Sentence |
denotes |
S glycoproteins engage 9-O-acetyl-SAs. |
T391 |
1089-1330 |
Sentence |
denotes |
The 9-O-acetyl SAs are the binding site for HCoV-OC43 S glycoprotein and related β-1 CoV S glycoproteins, however SA-binding sites on the 9-O-acetyl sialyl receptors of MERS-CoV S glycoprotein and HCoV-OC43 S glycoprotein are different [71]. |
T392 |
1331-1391 |
Sentence |
denotes |
Thus, CoVs use two different entry and attachment receptors. |
T393 |
1392-1528 |
Sentence |
denotes |
Therefore, S glycoproteins of CoVs are distinct from influenza virus A HAs, which bind to the Neu5Ac species by conserved binding sites. |
T394 |
1529-1782 |
Sentence |
denotes |
The ligand-binding sites of BCoV HE enzyme, influenza HEF enzyme and CoV S glycoprotein have evolved 9-O-Ac-SA binding through hydrogen bonding with the 9-O-acetyl carbonyl group and hydrophobic pocket formation with the 9-O-acetyl methyl group [71,72]. |
T395 |
1783-1863 |
Sentence |
denotes |
However, influenza HA cannot bind to 9-O-acetyl-SAs but can bind to NeuGcs [73]. |
T396 |
1864-2173 |
Sentence |
denotes |
The HCoV-OC43 S glycoprotein, HCoV-HKU1 S glycoprotein, BCoV S glycoprotein and PHEV S glycoprotein, therefore, share the ligand-binding specificity of influenza C/D HEF enzyme, although they are functionally more similar to influenza virus A/B HA, whereas CoV HE or influenza virus A/B NA have RDE activities |
T397 |
2174-2248 |
Sentence |
denotes |
CoV HEs are functionally similar to influenza virus C/D HEF glycoproteins. |
T398 |
2249-2423 |
Sentence |
denotes |
In CoV, the S glycoprotein recognizes the 9-O-Ac-SA sugar, while the HE acts as the RDE enzyme with SA-O-acetyl-esterase activity to release virions from infected host cells. |
T399 |
2424-2484 |
Sentence |
denotes |
For example, HCoV-OC43 also has a similar HE as an RDE [71]. |
T400 |
2485-2566 |
Sentence |
denotes |
In influenza C and D viruses, HEF glycoproteins act similarly to the CoV HE [74]. |
T401 |
2567-2629 |
Sentence |
denotes |
In influenza A virus, RDE NA releases virions from host cells. |
T402 |
2630-3051 |
Sentence |
denotes |
However, MERS-CoV does not have a similar enzyme and thus MER-CoV binding to SA receptors is mediated by energetically reversible interactions of the lipid rafts with increased SA receptors [75], thus enhancing dipeptidyl peptidase 4 (DPP4) or carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) recognition power and viral entry [76] and membrane-associated 78-kDa glucose-regulated protein (GRP78) [77]. |
T403 |
3052-3179 |
Sentence |
denotes |
MERS-CoV S glycoprotein can hemagglutinate human erythrocytes and mediates virus entry into human respiratory epithelial cells. |
T404 |
3180-3329 |
Sentence |
denotes |
MERS-CoV S glycoprotein attachment is not observed for 9-O-acetylated or 5-N-glycolyl SAs, but is observed for α2,3-SA linkage over α2,6-SA linkages. |
T405 |
3330-3493 |
Sentence |
denotes |
SA-binding sites of MERS-CoV S glycoprotein and HCoV-OC43 S glycoprotein are not conserved [78], although they engage α2,3-SAs on the avian host cell surface [79]. |
T406 |
3494-3599 |
Sentence |
denotes |
MERS-CoV recognizes α2,3-SA and to a lesser extent the α2,6-SAs and sulfated SLeX for binding preference. |
T407 |
3600-3668 |
Sentence |
denotes |
Thus, S glycoproteins may have independently evolved SA recognition. |
T408 |
3669-3952 |
Sentence |
denotes |
The acquisition of SA-binding ability of MERS-CoV S seems to be an evolutionarily recent event, because HKU4 S1 and HKU5 S1 cannot hemagglutinate human erythrocytes [75], indicating flexible evolutionary exchange allowing cross-species transmission towards host cell tropism of CoVs. |
T409 |
3953-4128 |
Sentence |
denotes |
In conclusion, CoV recognition of 9-O-Ac-SAs for infection is based on a conserved sequence for engagement of SA-related carbohydrate ligands across CoVs and orthomyxoviruses. |