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Vaccinia virus temperature-sensitive mutants in the A28 gene produce non-infectious virions that bind to cells but are defective in entry.

ABSTRACT: The vaccinia virus temperature-sensitive mutations Cts6 and Cts9 were mapped by marker rescue and DNA sequencing to the A28 gene. Cts6 and Cts9 contain an identical 2-bp deletion truncating the A28 protein and removing the fourth conserved cysteine near the C-terminus. Cts9 mutant virions produced at 40 degrees C were non-infectious and unable to cause cytopathic effect. However, the mutant A28 protein localized to purified mature virions (MV) at 31 degrees C and 40 degrees C. MV of Cts9 produced at 40 degrees C bound to cells but did not enter cells. Low pH treatment of Cts9-infected cells at 18 h p.i. failed to produce fusion from within at 40 degrees C, but gave fusion at 31 degrees C. Adsorption of Cts9 mutant virions to cells followed by low pH treatment showed a defect in fusion from without. The Cts9 phenotype suggests that the A28 protein is involved in both virus entry and cell-cell fusion, and supports the linkage between the two processes.

SUBMITTER: Turner PC

PROVIDER: S-EPMC2062567 | biostudies-literature | 2007 Sep

REPOSITORIES: biostudies-literature

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Vaccinia virus temperature-sensitive mutants in the A28 gene produce non-infectious virions that bind to cells but are defective in entry.

Turner Peter C PC Dilling Bradley P BP Prins Cindy C Cresawn Steven G SG Moyer Richard W RW Condit Richard C RC

Virology 20070517 1

The vaccinia virus temperature-sensitive mutations Cts6 and Cts9 were mapped by marker rescue and DNA sequencing to the A28 gene. Cts6 and Cts9 contain an identical 2-bp deletion truncating the A28 protein and removing the fourth conserved cysteine near the C-terminus. Cts9 mutant virions produced at 40 degrees C were non-infectious and unable to cause cytopathic effect. However, the mutant A28 protein localized to purified mature virions (MV) at 31 degrees C and 40 degrees C. MV of Cts9 produce ...[more]

PMID: 17499330

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Project description:Vaccinia virus assembly in the cytoplasm of infected cells involves the formation of a biconcave viral core inside the maturing viral particle. The boundary of the core is defined by a pseudohexagonal palisade layer, composed of trimers projecting from an inner wall. To understand the assembly of this complex core architecture, we obtained a subnanometer structure of the palisade trimer by cryo-electron tomography and subtomogram averaging of purified intact virions. Using AlphaFold2 structure predictions, we determined that the palisade is formed from trimers of the proteolytically processed form of the viral protein A10. In addition, we found that each A10 protomer associates with an α-helix (residues 24-66) of A4. Cellular localization assays outside the context of infection demonstrate that the A4 N-terminus is necessary and sufficient to interact with A10. The interaction between A4 and A10 provides insights into how the palisade layer might become tightly associated with the viral membrane during virion maturation. Reconstruction of the palisade layer reveals that, despite local hexagonal ordering, the A10/A4 trimers are widely spaced, suggesting that additional components organize the lattice. This spacing would, however, allow the adoption of the characteristic biconcave shape of the viral core. Finally, we also found that the palisade incorporates multiple copies of a hexameric portal structure. We suggest that these portals are formed by E6, a viral protein that is essential for virion assembly and required to release viral mRNA from the core early in infection.IMPORTANCEPoxviruses such as variola virus (smallpox) and monkeypox cause diseases in humans. Other poxviruses, including vaccinia and modified vaccinia Ankara, are used as vaccine vectors. Given their importance, a greater structural understanding of poxvirus virions is needed. We now performed cryo-electron tomography of purified intact vaccinia virions to study the structure of the palisade, a protein lattice that defines the viral core boundary. We identified the main viral proteins that form the palisade and their interaction surfaces and provided new insights into the organization of the viral core.

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Vaccinia virus temperature-sensitive mutants in the A28 gene produce non-infectious virions that bind to cells but are defective in entry.

Publications

Vaccinia virus temperature-sensitive mutants in the A28 gene produce non-infectious virions that bind to cells but are defective in entry.

Similar Datasets

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