Simian virus 40 associates with nuclear superstructures at early times of infection

Abstract

The association of infecting simian virus 40 with insoluble nuclear structures was assayed by disrupting infected nuclei and assaying insoluble fractions for virus. Three methods were used which lyse nuclei but maintain the insolubility of residual nuclear structures: sonication, high-salt-Triton-EDTA extraction, and low-salt-lithium diiodosalicylate extraction. After each type of nuclear extraction, infecting simian virus 40 remained associated with the residual nuclear structures. This association depended strictly on natural viral infections and on the use of buffers containing moderate amounts of salt and Mg2+ for the isolation of infected nuclei. These viral interactions exhibited behavior similar to host cell DNA interactions studied by analogous assays. Both viral DNA and coat proteins were found associated with the host cell nuclear superstructure. We conclude that at early times after infection the viral templates mimic the state of the host cell chromatin by attaching to the cellular nuclear matrix.

Simian virus 40 T-antigen DNA helicase is a hexamer which forms a binary complex during bidirectional unwinding from the viral origin of DNA replication

“…Moreover, the DNA helicase could function as an organizer of the replication machine and at the same time could fix it to the nuclear scaffold, possibly arranged in replication centers with multiple replication forks as has been suggested recently for viral and cellular DNA (13,24,34,54). Accordingly, the (transient) binding of replication origins, as well as replicating DNA, to structural elements has been described (18,21,26,55; for a review, see reference 53), and during a lytic infection, a subfraction of T antigen is bound to the nuclear matrix and has been suggested to be actively involved in SV40 DNA replication (42,43,57). In this context, it is also interesting to note the frequent colocalization of detected replication origins with matrix attachment sites (1-3, 9).…”

Structural topography of simian virus 40 DNA replication

“…We next wanted to analyze the interaction of SV40 DNA with nuclear structures in terms of a functional characterization of replicating SV40 DNA. As a prerequisite, we first tested the effects of temperature, Mg2+, and high salt during nuclear matrix preparation, since these parameters were reported to influence the integrity of nuclear structures as well as the extractability of viral DNA (3,4,20,26,52).…”

cis-acting sequences that control the level of viral DNA synthesis in the polyomavirus late region

“…The chromatin and genetic organization of Py and of the closely related monkey virus simian virus 40 have been thoroughly studied in an effort to clarify the structurefunction relationships of these viral genomes (2,8,11,19). A recent report (4) describes a Py mutation mapping in the late region that confers a growth advantage to the mutant over the wt.…”