Bovine papillomavirus E1 protein can, by itself, efficiently drive multiple rounds of DNA synthesis in vitro

Bonne-Andréa, Catherine; Santucci, S; Clertant, Philippe

doi:10.1128/jvi.69.5.3201-3205.1995

Cited by 38 publications

(24 citation statements)

References 33 publications

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“…Thus, a BPV-1 replicon can replicate in cells in the absence of E2TA when sufficient wild-type E1 protein is present. This result is consistent with that seen when the E1 gene of HPV-1 is overexpressed in similar transient replication assays in tissue culture cells (11) and correlates with the dispensability of E2TA in in vitro BPV-1 DNA replication assays (3,27,37,47). When efficiently expressed in trans from the CMV immediate-early promoter, several of the E1 mutants (R370T, F542V, L466H, and D497A/G498A) that did not support replication in the context of the full-length viral genome could support replication in C33A cells (Fig.…”

Section: Resultssupporting

confidence: 88%

Bovine papillomavirus type 1 E1 and simian virus 40 large T antigen share regions of sequence similarity required for multiple functions

Mansky

Batiza

Lambert

1997

J Virol

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The full-length product of the bovine papillomavirus type 1 (BPV-1) E1 translational open reading frame is required for viral DNA replication in vivo and in vitro. E1 is a multifunctional protein whose properties include ATP binding, acting as an ATPase-dependent DNA helicase, DNA binding to the BPV-1 origin of viral DNA replication, and association with the E2 transcriptional transactivator, E2TA, a second viral protein involved in DNA replication. All of these properties are thought to be important for E1's role in replicating the viral genome. In addition BPV-1 E1 can inhibit activation of the viral P 89 promoter by the BPV-1 E2TA. E1 has amino acid homology with eight regions of SV40 large tumor antigen (T-ag), a DNA helicase that is essential for the replication of the SV40 DNA genome. These eight regions of similarity lie within the domain of T-ag that confers DNA helicase activity. We created a series of missense mutations in BPV-1 E1 at codons 295, 344-345, 446, 464, 466, 497-498, 523, and 542, which encode amino acids of identity in seven of the eight regions of similarity between E1 and T-ag, and at codon 370. The activities of these mutant E1 genes were compared to wild-type E1 in multiple assays that measured DNA replication, inhibition of E2TA-dependent transcription, DNA binding, ATP binding, and protein expression. Based upon these analyses, the following conclusions were made: (i) at least five of the eight regions in E1 that are similar to regions in T-ag are functionally important in viral DNA replication; (ii) specific E1 missense mutants, themselves defective for supporting DNA replication, could act in trans to suppress the replication function of wild-type E1; (iii) certain regions of similarity with T-ag that are important for E1's ability to support DNA replication are not necessary for its capacity to inhibit E2TA-dependent transcription; and (iv) efficient DNA binding by E1 is not essential for E1 to inhibit E2TA-dependent transcription.

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Section: Resultssupporting

confidence: 88%

Bovine papillomavirus type 1 E1 and simian virus 40 large T antigen share regions of sequence similarity required for multiple functions

Mansky

Batiza

Lambert

1997

J Virol

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“…A similar, if not identical, set of cellular replication factors and enzymes, in addition to viral initiator proteins, is utilized by SV40 (Tsurimoto et al, 1990;Weinberg et al, 1990) and bovine papillomavirus-1 (Muller et al, 1994) at the origin of replication to initiate DNA synthesis. Analysis of the essential cis sequences shows that the BPV-1 minimal origin (MO) (Ustav et al, 1993) resembles a typical eukaryotic origin of replication (DePamphilis, 1993) and it has been suggested that this similarity could also be extended to the mechanisms of replication of all papovaviruses (Nallaseth and DePamphilis, 1994;Bonne-Andrea et al, 1995). However, the ability of the papillomaviruses to be stably maintained as plasmids distinguishes them from other papovaviruses.…”

Section: Introductionmentioning

confidence: 99%

Cis and trans requirements for stable episomal maintenance of the BPV-1 replicator.

et al. 1996

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Papillomavirus genomes are maintained as multicopy nuclear plasmids in transformed cells. To address the mechanisms by which the viral DNA is stably propagated in the transformed cells, we have constructed a cell line CH04.15 expressing constitutively the viral proteins E1 and E2, that are required for initiation of viral DNA replication. We show that these viral proteins are necessary and sufficient for stable extrachromosomal replication. Using the cell line CH04.15, we have shown that the bovine papillomavirus‐1 (BPV‐1) minimal origin of replication (MO) is absolutely necessary, but is not sufficient for stable extrachromosomal replication of viral plasmids. By deletion and insertion analysis, we identified an additional element (minichromosome maintenance element, MME) in the upstream regulatory region of BPV‐1 which assures stable replication of the MO‐containing plasmids. This element is composed of multiple binding sites for the transcription activator E2. MME appears to function in the absence of replication but requires E1 and E2 proteins for activity. In contrast to, for example, Epstein‐Barr virus oriP, stably maintained BPV‐1 plasmids are not subject to once‐per‐cell cycle replication as determined by density labelling experiments. These results indicate that papillomavirus episomal replicators replicate independently of the chromosomal DNA of their hosts.

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“…The bovine papillomavirus type 1 (BPV-1) E1 protein is an essential viral DNA replication factor that is both an origin recognition protein (5,6,13,17,18,20) and an ATP-dependent helicase (14,21). E1 binds to an 18-bp inverted repeat element (5) and presumably initiates DNA replication both by unwinding the origin duplex DNA and by recruiting cellular replication factors such as DNA polymerase ␣ (3,11) to the initiation complex. In vitro, E1 alone is sufficient to initiate replication (3), but in vivo the viral full-length E2 transcriptional activator protein is also absolutely required (16).…”

mentioning

confidence: 99%

“…E1 binds to an 18-bp inverted repeat element (5) and presumably initiates DNA replication both by unwinding the origin duplex DNA and by recruiting cellular replication factors such as DNA polymerase ␣ (3,11) to the initiation complex. In vitro, E1 alone is sufficient to initiate replication (3), but in vivo the viral full-length E2 transcriptional activator protein is also absolutely required (16). E1 can form complexes with the E2 protein (2,8,15,20), and both binding to and unwinding of origin DNA by E1 is enhanced by these cooperative interactions with E2 (4,9,13,20).…”

mentioning

confidence: 99%

Isolation of an amino-terminal region of bovine papillomavirus type 1 E1 protein that retains origin binding and E2 interaction capacity

Leng

Ludes-Meyers

Wilson

1997

J Virol

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In vitro DNA binding results from a series of E1 proteins containing amino-terminal or carboxy-terminal truncations indicated that sequences between amino acids 121 and 284 were critical for origin binding. Additional binding experiments with E1 proteins containing internal, in-frame insertions or deletions confirmed the importance of the region defined by truncated E1 proteins and also demonstrated that downstream sequences were not required for binding activity in the context of the full-length E1 protein. On the basis of mapping results from the E1 mutants, a clone (pE1 121-311 ) was constructed that expressed E1 amino acids within the approximate boundaries of the critical sequences for DNA binding. The E1 121-311 protein retained origin-specific DNA binding, confirming that this region was not only necessary but was also sufficient for origin recognition. In addition to origin binding, E1 121-311 bound E2 protein in a cold-sensitive manner. Therefore, DNA binding and E2 binding activities colocalize to a 191-amino-acid functional domain derived from the amino-terminal half of the E1 protein. Finally, three E1 proteins with mutations in this region all lacked DNA binding activity and were all defective for in vivo replication. Two of these E1 mutants retained E2 binding capability, demonstrating that origin recognition by E1 is critical for replication and cannot necessarily be rescued by an interaction with E2 protein.

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Bovine papillomavirus E1 protein can, by itself, efficiently drive multiple rounds of DNA synthesis in vitro

Cited by 38 publications

References 33 publications

Bovine papillomavirus type 1 E1 and simian virus 40 large T antigen share regions of sequence similarity required for multiple functions

Bovine papillomavirus type 1 E1 and simian virus 40 large T antigen share regions of sequence similarity required for multiple functions

Cis and trans requirements for stable episomal maintenance of the BPV-1 replicator.

Isolation of an amino-terminal region of bovine papillomavirus type 1 E1 protein that retains origin binding and E2 interaction capacity

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