DNA-binding Proteins Induced by the Cottontail Rabbit Herpesvirus CTHV

Abstract

SUMMARYSeveral new polypeptides were detected in cells infected with CTHV, a cottontail rabbit herpesvirus. All of them (Mr 150K, ll0K, 93K, 83K, 75K and 35K) accumulated in the nucleus during the infectious cycle, and all except the 150K species bound to DNA-cellulose affinity columns in low-salt buffers. Polyclonal antisera prepared against the 35K DNA-binding protein also recognized the 75K species. Although the 75K protein could be detected earlier in infection than the 35K protein, late in the infectious cycle the latter increased to an abundance approaching that of cellular histones. Treatment of partially purified virions with a non-ionic detergent indicated that the 35K protein, but not the 75K protein, is a component of capsid/ tegument structures. The anti-35K/75K serum did not cross-react with herpesvirus sylvilagus virion proteins, which, in an electrophoretic comparison, exhibited both similarities to and differences from the virion proteins of CTHV. Labelling of CTHVinfected cells with [32p]orthophosphate revealed the presence of phosphoproteins electrophoretically comigrating with the 93K, 83K, 75K and 35K proteins.

Partial characterization of two serologically related DNA-binding proteins specified by the cottontail rabbit herpesvirus CTHV

“…We have already shown 35 kDa and 75 kDa are recognized by the same antibody [5]. After digestion by protease V8, the only peptide showing substantial reactivity was the 10 kDa component in the digests of the 35 kDa protein (Fig.…”

“…As shown in Figs. 1 b, c several major methionine-containing peptides with estimated masses from 8 kDa to 15 kDa [35S]methionine-labelled proteins were extracted from CTHV-infected RK13 cells as previously described [5]. After migration through a 15% acrylamide SDS gel, the 75 kDa and 35 kDa bands were excised.…”

“…The basic structure of the CTHV genome consists of two G+C-poor coding regions flanked by multiple copies of a G+C-rich repeat unit [6]. In order to study whether DNA-protein interactions might be involved in the origin and the maintenance of the G+C content differences, we studied nuclear proteins extracted from CTHV infected cells [5]. An abundant 35 kDa DNA-binding protein (DBP) was found to be serologically related to a 75 kDa DBP which appeared substantially earlier in the infectious cycle, although the latter did not, even at later times, attain the abundance of the former.…”