EMD-43671
Soluble ectodomain of human cytomegalovirus (HCMV) glycoprotein B (gB) stabilized in a prefusion-like conformation in complex with 1G2 and 7H3, local refinement
EMD-43671
Single-particle3.1 Å
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Map released: 18/09/2024
Last modified: 18/09/2024
Sample Organism:
Homo sapiens,
Human betaherpesvirus 5
Sample: Soluble ectodomain of human cytomegalovirus (HCMV) glycoprotein B (gB) stabilized in a prefusion-like conformation in complex with 1G2 and 7H3
Deposition Authors: Sponholtz MR
,
Byrne PO
,
McLellan JS
Sample: Soluble ectodomain of human cytomegalovirus (HCMV) glycoprotein B (gB) stabilized in a prefusion-like conformation in complex with 1G2 and 7H3
Deposition Authors: Sponholtz MR
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Structure-based design of a soluble human cytomegalovirus glycoprotein B antigen stabilized in a prefusion-like conformation.
Sponholtz MR
,
Byrne PO
,
Lee AG
,
Ramamohan AR
,
Goldsmith JA,
McCool RS
,
Zhou L
,
Johnson NV
,
Hsieh CL,
Connors M
,
Karthigeyan KP,
Crooks CM
,
Fuller AS,
Campbell JD,
Permar SR,
Maynard JA
,
Yu D,
Bottomley MJ
,
McLellan JS
(2024) PNAS , 121 , e2404250121 - e2404250121
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(2024) PNAS , 121 , e2404250121 - e2404250121
Abstract:
Human cytomegalovirus (HCMV) glycoprotein B (gB) is a class III membrane fusion protein required for viral entry. HCMV vaccine candidates containing gB have demonstrated moderate clinical efficacy, but no HCMV vaccine has been approved. Here, we used structure-based design to identify and characterize amino acid substitutions that stabilize gB in its metastable prefusion conformation. One variant containing two engineered interprotomer disulfide bonds and two cavity-filling substitutions (gB-C7), displayed increased expression and thermostability. A 2.8 Å resolution cryoelectron microscopy structure shows that gB-C7 adopts a prefusion-like conformation, revealing additional structural elements at the membrane-distal apex. Unlike previous observations for several class I viral fusion proteins, mice immunized with postfusion or prefusion-stabilized forms of soluble gB protein displayed similar neutralizing antibody titers, here specifically against an HCMV laboratory strain on fibroblasts. Collectively, these results identify initial strategies to stabilize class III viral fusion proteins and provide tools to probe gB-directed antibody responses.
Human cytomegalovirus (HCMV) glycoprotein B (gB) is a class III membrane fusion protein required for viral entry. HCMV vaccine candidates containing gB have demonstrated moderate clinical efficacy, but no HCMV vaccine has been approved. Here, we used structure-based design to identify and characterize amino acid substitutions that stabilize gB in its metastable prefusion conformation. One variant containing two engineered interprotomer disulfide bonds and two cavity-filling substitutions (gB-C7), displayed increased expression and thermostability. A 2.8 Å resolution cryoelectron microscopy structure shows that gB-C7 adopts a prefusion-like conformation, revealing additional structural elements at the membrane-distal apex. Unlike previous observations for several class I viral fusion proteins, mice immunized with postfusion or prefusion-stabilized forms of soluble gB protein displayed similar neutralizing antibody titers, here specifically against an HCMV laboratory strain on fibroblasts. Collectively, these results identify initial strategies to stabilize class III viral fusion proteins and provide tools to probe gB-directed antibody responses.