The large tegument protein pUL36 is essential for formation of the capsid vertex-specific component at the capsid-tegument interface of herpes simplex virus 1.
Bottom Line: In addition, the presence of full-length pUL36 results in weak density that extends the CVSC toward the penton, suggesting either that this extra density is formed directly by pUL36 or that pUL36 stabilizes other components of the vertex-tegument interface.Herpesviruses have complex particles that are formed as a result of a carefully controlled sequence of assembly steps.We show that the largest viral protein, pUL36, which occupies the layer of tegument closest to the capsid, is essential for formation of structurally normal connections to the capsid.
Affiliation: MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom.Show MeSH
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Mentions: As has been noted previously, the icosahedrally ordered vertex densities seen in reconstructions of intact virions are not large enough to account for all the mass of the tegument proteins that are thought to be involved (28, 40). The presence of less ordered parts of the proteins, which are evident in density maps of the capsid vertices (see Fig. S3 in the supplemental material), makes the appearance of the CVSC as displayed by surface representation sensitive to the threshold at which they are viewed. Lowering the density threshold from the mean + 1 σ to the mean + 0.2 σ had little effect on the appearance of the ARΔUL36 (Fig. 5) and KΔUL36 (data not shown) CVSCs, which remained small and never approached the size of the archetypal CVSC seen on nuclear C-capsids (36). In contrast, reducing the threshold of the WT and FRΔUL37 capsid maps resulted in large increases in the size of the CVSC, which extended much further in the direction of the penton (Fig. 5). Interestingly, this was not the case for vRR1072 capsids, where the CVSC showed only a marginal increase in size at the lower threshold (Fig. 5).
Affiliation: MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom.