Structural basis for the physiological temperature dependence of the association of VP16 with the cytoplasmic tail of herpes simplex virus glycoprotein H.
Critical events in the life cycle of herpes simplex virus (HSV) are the binding of cytoplasmic capsids to cellular organelles and subsequent envelopment. Work from several laboratories suggests that these events occur as a result of a network of partially redundant interactions among the capsid surface, tegument components, and cytoplasmic tails of virally encoded glycoproteins. Consistent with this model, we previously showed that tegument protein VP16 can specifically interact with the cytoplasmic tail of envelope protein gH in vitro and in vivo when fused to glutathione S-transferase and to green fluorescent protein, respectively. In both instances, this association was strikingly temperature dependent: binding occurred only at 37 degrees C and not at lower temperatures. Here we demonstrate that virally expressed full-length gH and VP16 can be coimmunoprecipitated from HSV-infected cells and that this association is also critically dependent upon the physiological temperature. To investigate the basis of this temperature requirement, we performed one- and two-dimensional nuclear magnetic resonance spectroscopy on peptides with the sequence of the gH tail. We found that the gH tail is disorganized at temperatures permissive for binding but becomes structured at lower temperatures. Furthermore, a mutated tail unable to adopt this rigid conformation binds VP16 even at 4 degrees C. We hypothesize that the gH tail is unstructured under physiological conditions in order to maximize the number of potential tegument partners with which it may associate. Being initially disordered, the gH tail may adopt one of several induced conformations as it associates with VP16 or alternative components of the tegument, maximizing redundancy during particle assembly.
Kamen
Douglas E
DE
Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, New York, NY 10461, USA. wilson@aecom.yu.edu
Gross
Sarah T
ST
Girvin
Mark E
ME
Wilson
Duncan W
DW
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D003593:Cytoplasm / Q000378:metabolism*; D017405:Herpes Simplex Virus Protein Vmw65 / Q000378:metabolism*; D018259:Herpesvirus 1, Human / Q000378:metabolism / Q000502:physiology*; D008956:Models, Chemical; D011485:Protein Binding; D013696:Temperature; D014709:Vero Cells; D014759:Viral Envelope Proteins / Q000737:chemistry / Q000378:metabolism*; D019065:Virus Assembly
D017405:Herpes Simplex Virus Protein Vmw65; D014759:Viral Envelope Proteins; C044200:glycoprotein H, herpes simplex virus type 1