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Publication Abstract from PubMed

The tripartite terminase complex of herperviruses assembles in the cytoplasm of infected cells and exploits the host nuclear import machinery to gain access to the nucleus, where capsid assembly and genome-packaging occur. Here, we analyzed the structure and conservation of Nuclear Localization Signal (NLS) sequences previously identified in Herpes Simplex Virus 1 (HSV-1) large terminase and Human Cytomegalovirus (HCMV) small terminase. We found a monopartite NLS at the N-terminus of large terminase, flanking the ATPase domain, that is conserved only in alpha-herpesviruses. In contrast, small terminase exposes a classical NLS at the far C-terminus of its helical structure, which is conserved only in two genera of the beta-subfamily and absent in alpha- and gamma-herpesviruses. In addition, we predicted a classical NLS in the third terminase subunit that is partially conserved among herpesviruses. Bioinformatic analysis revealed that both location and potency of NLSs in terminase subunits evolved more rapidly than the rest of the aminoacid sequence, despite the selective pressure to keep terminase gene products active and localized in the nucleus. We propose that swapping NLSs among terminase subunits is a regulatory mechanism that allows different herpesviruses to regulate the kinetics of terminase nuclear import, reflecting a mechanism of virus:host adaptation.

Divergent Evolution of Nuclear Localization Signal Sequences in Herpesvirus Terminase Subunits.,Sankhala RS, Lokareddy RK, Cingolani G J Biol Chem. 2016 Mar 31. pii: jbc.M116.724393. PMID:27033706^[1]

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