6t3z

Publication Abstract from PubMed

Herpesviruses uniquely express two essential nuclear egress-regulating proteins forming a heterodimeric basic structure of the nuclear-egress complex (core NEC). These core NECs serve as a hexameric lattice-structured platform for capsid docking and recruit viral and cellular NEC-associated factors that jointly exert nuclear lamina- and membrane-rearranging functions (multicomponent NEC). Here, we report the X-ray structures of beta- and gamma-herpesvirus core NECs obtained through an innovative recombinant expression strategy based on NEC-hook::NEC-groove protein fusion constructs. This approach yielded the first structure of gamma-herpesviral core NEC, namely the 1.56 A structure of Epstein-Barr virus (EBV) BFRF1-BFLF2, as well as an increased resolution 1.48 A structure of human cytomegalovirus (HCMV) pUL50-pUL53. Detailed analysis of these structures revealed that the prominent hook segment is absolutely required for core NEC formation and contributes approx. 80% of the interaction surface of the globular domains of NEC proteins. Moreover, using HCMV::EBV hook domain swap constructs, computational prediction of the roles of individual hook residues for binding, and quantitative binding assays with synthetic peptides presenting the HCMV- and EBV-specific NEC hook sequences, we characterized the unique hook-into-groove NEC interaction at various levels. Although the overall physicochemical characteristics of the protein interfaces differ considerably in these beta- and gamma-herpesvirus NECs, the binding free energy contributions of residues displayed from identical positions are similar. In summary, the results of our study reveal critical details of the molecular mechanism of herpesviral NEC interactions and highlight their potential as an antiviral drug target.

High-resolution crystal structures of two prototypical beta- and gamma-herpesviral nuclear egress complexes unravel the determinants of subfamily specificity.,Muller YA, Hage S, Alkhashrom S, Hollriegl T, Weigert S, Dolles S, Hof K, Walzer SA, Egerer-Sieber C, Conrad M, Holst S, Losing J, Sonntag E, Sticht H, Eichler J, Marschall M J Biol Chem. 2020 Jan 24. pii: RA119.011546. doi: 10.1074/jbc.RA119.011546. PMID:31980459^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.