4hsi | pdb_00004hsi
Glycoprotein B from Herpes simplex virus type 1, A504P/R505G/Q507G/N511G mutant, low-pH
Structural highlights
FunctionGB_HHV1K Envelope glycoprotein that forms spikes at the surface of virion envelope. Essential for the initial attachment to heparan sulfate moities of the host cell surface proteoglycans. Involved in fusion of viral and cellular membranes leading to virus entry into the host cell. Following initial binding of gD to one of its receptors, membrane fusion is mediated by the fusion machinery composed at least of gB and the heterodimer gH/gL. May also be involved in the fusion between the virion envelope and the outer nuclear membrane during virion egress. Also plays a role, together with gK, in virus-induced cell-to-cell fusion (syncytia formation).[1] Publication Abstract from PubMedViral fusogens mediate the merger of the viral envelope and cellular membrane during viral entry. These proteins share little sequence similarity but all are thought to act by refolding through a series of conformational intermediates from the metastable prefusion form to the stable postfusion form. Crystal structures of both prefusion and postfusion forms have illuminated the conformational pathways of several viral fusogens. By contrast, only the structure of the postfusion form is available for glycoprotein B (gB), the conserved fusogen of herpesviruses. To gain insight into the nature of the fusogenic conformational changes in gB, we used several approaches aimed at engineering the prefusion form of the HSV-1 gB ectodomain, including modifications intended to stabilize the prefusion form and novel mutations aimed at destabilizing the postfusion form. We found that the postfusion conformation of gB is remarkably stable and resistant to perturbations. Several mutations successfully destabilized the gB trimer, identifying regions that are critical for the stability of the postfusion form. Yet, none of the constructs adopted the prefusion conformation. We propose that the soluble ectodomain of gB folds into the postfusion form without first adopting the prefusion intermediate. These results suggest that other regions of gB, including the transmembrane region and the cytoplasmic domain, may be necessary to establish and maintain the metastable prefusion conformation. Extensive mutagenesis of the HSV-1 gB ectodomain reveals remarkable stability of its postfusion form.,Vitu E, Sharma S, Stampfer SD, Heldwein EE J Mol Biol. 2013 Mar 8. pii: S0022-2836(13)00147-2. doi:, 10.1016/j.jmb.2013.03.001. PMID:23500487[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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