JGV Direct - HSV-1 VP22 interacts with TAF-I proteins (H. van Leeuwen and others)

								ARTICLE ABSTRACT
								DOI: 10.1099/vir.0.19326-0
								Online 12 June 2003

Herpes simplex virus type 1 tegument protein VP22 interacts with TAF-I proteins and inhibits nucleosome assembly but not regulation of histone acetylation by INHAT

Hans van Leeuwen,¹ Mitsuru Okuwaki,² Rui Hong,³ Debabrata Chakravarti,³ Kyosuke Nagata² and Peter O'Hare¹

¹Marie Curie Research Institute, The Chart, Oxted, Surrey RH8 0TL, UK
²Department of Infection Biology, Institute of Basic Medical Sciences, University of Tsukuba, 1-1-1 Tennohdai, Tsukuba 305-8575, Japan
³Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA

Affinity chromatography was used to identify cellular proteins that interact with the herpes simplex virus (HSV) tegument protein VP22. Among a small set of proteins that bind specifically to VP22, we identified TAF-I (template-activating factor I), a chromatin remodelling protein and close homologue of the histone chaperone protein NAP-1. TAF-I has been shown previously to promote more ordered transfer of histones to naked DNA through a direct interaction with histones. TAF-I, as a subunit of the INHAT (inhibitor of acetyltransferases) protein complex, also binds to histones and masks them from being substrates for the acetyltransferases p300 and PCAF. Using in vitro assays for TAF-I activity in chromatin assembly, we show that VP22 inhibits nucleosome deposition on DNA by binding to TAF-I. We also observed that VP22 binds non-specifically to DNA, an activity that is abolished by TAF-I. However, the presence of VP22 does not affect the property of INHAT in inhibiting the histone acetyltransferase activity of p300 or PCAF in vitro. We speculate that this interaction could be relevant to HSV DNA organization early in infection, for example, by interfering with nucleosomal deposition on the genome. Consistent with this possibility was the observation that overexpression of TAF-I in transfected cells interferes with the progression of HSV-1 infection.

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This article is now available in the September 2003 print issue of JGV (vol. 84, 2501–2510). The complete issue of the journal may be seen in electronic form on JGV Online.