Open reading frames UL44, IRS1/TRS1, and UL36-38 are required for transient complementation of human cytomegalovirus oriLyt-dependent DNA synthesis.

AUTOR(ES)

Pari, G S

RESUMO

Previous results showed that plasmids containing human cytomegalovirus (HCMV) oriLyt are replicated after transfection into permissive cells if essential trans-acting factors are supplied by HCMV infection (D. G. Anders, M. A. Kacica, G. S. Pari, and S. M. Punturieri, J. Virol. 66:3373-3384, 1992). We have now used oriLyt as a reporter of HCMV DNA replication in a transient complementation assay in which cotransfected cosmid clones, instead of HCMV infection, provided essential trans-acting factors. Complemented replication was oriLyt dependent and phosphonoformic acid sensitive and produced tandem arrays typical of HCMV lytic-phase DNA synthesis. Thus, this assay provides a valid genetic test to find previously unidentified genes that are essential for DNA synthesis and to corroborate functional predictions made by nucleotide sequence comparisons and biochemical analyses. Five cosmids were necessary and sufficient to produce origin-dependent DNA synthesis; all but one of these required cosmids contain at least one candidate homolog of herpes simplex virus type 1 replication genes. We further used the assay to define essential regions in two of the required cosmids, pCM1017 and pCM1052. Results presented show that UL44, proposed on the basis of biochemical evidence to be the HCMV DNA polymerase accessory protein, was required for complementation. In addition, three genomic regions encoding regulatory proteins also were needed to produce origin-dependent DNA synthesis in this assay: (i) IRS1/TRS1, which cooperates with the major immediate-early proteins to activate UL44 expression; (ii) UL36-38; and (iii) the major immediate-early region comprising IE1 and IE2. Combined, these results unequivocally establish the utility of this approach for mapping HCMV replication genes. Thus, it will now be possible to define the set of HCMV genes necessary and sufficient for initiating and performing lytic-phase DNA synthesis as well as to identify those virus genes needed for their expression in human fibroblasts.

Documentos Relacionados

• Eleven loci encoding trans-acting factors are required for transient complementation of human cytomegalovirus oriLyt-dependent DNA replication.
• Human cytomegalovirus US3 and UL36-38 immediate-early proteins regulate gene expression.
• Human Cytomegalovirus UL84 Oligomerization and Heterodimerization Domains Act as Transdominant Inhibitors of oriLyt-Dependent DNA Replication: Evidence that IE2-UL84 and UL84-UL84 Interactions Are Required for Lytic DNA Replication
• Evidence that the UL84 gene product of human cytomegalovirus is essential for promoting oriLyt-dependent DNA replication and formation of replication compartments in cotransfection assays.
• Human cytomegalovirus UL36-38 and US3 immediate-early genes: temporally regulated expression of nuclear, cytoplasmic, and polysome-associated transcripts during infection.