DNA Recognition by the Herpes Simplex Virus Transactivator VP16: a Novel DNA-Binding Structure

Abstract

Upon infection, the herpes simplex virus (HSV) transcriptional activator VP16 directs the formation of a multiprotein-DNA complex—the VP16-induced complex—with two cellular proteins, the host cell factor HCF-1 and the POU domain transcription factor Oct-1, on TAATGARAT-containing sequences found in the promoters of HSV immediate-early genes. HSV VP16 contains carboxy-terminal sequences important for transcriptional activation and a central conserved core that is important for VP16-induced complex assembly. On its own, VP16 displays little, if any, sequence-specific DNA-binding activity. We show here that, within the VP16-induced complex, however, the VP16 core has an important role in DNA binding. Mutation of basic residues on the surface of the VP16 core reveals a novel DNA-binding surface with essential residues which are conserved among VP16 orthologs. These results illuminate how, through association with DNA, VP16 is able to interpret cis-regulatory signals in the DNA to direct the assembly of a multiprotein-DNA transcriptional regulatory complex.

ACKNOWLEDGMENTS

We thank X. Cheng for discussions; A. Bubulya for help with the in vivo transcriptional activation studies; C. Sanders for advice on chemical DNA sequencing; L. Joshua-Tor and M. Wang for help with the VP16 structural similarity analysis; X. Zhao for HeLa cell nuclear extract; N. Hernandez, L. Joshua-Tor, A. Stenlund, and J. Wysocka for comments on the manuscript; J. Duffy and P. Renna for artwork; and J. Reader for help with manuscript preparation.

These studies were funded by U.S. Public Health Service grant CA-13106 from the National Cancer Institute.