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At least 829 records · Page 46Linked to original sources
PubMed1993

RNA-dependent replication, transcription, and persistence of brome mosaic virus RNA replicons in S. cerevisiae.

This paper shows that yeast can be a host for the replication of a higher eukaryotic viral genome. Brome mosaic virus (BMV) is a member of the alphavirus-like superfamily of animal and plant positive strand RNA viruses. Yeast expressing BMV RNA replication genes 1a and 2a support RNA-dependent replication and transcription of BMV RNA3 derivatives. RNA3 derivatives with the coat gene replaced by a reporter gene expressed that gene in a fashion dependent on 1a and 2a expression in trans and on BMV RNA replication and transcription signals in cis. RNA3 derivatives carrying the yeast URA3 gene complemented ura3- yeast to prototrophy and were maintained as persistent RNA episomes. Thus, all cellular factors essential for BMV RNA replication and transcription must be present in yeast, and yeast genetics should facilitate their identification.

Base Sequence↗
PubMed1985

Expression of the cloned subunits of bacterial luciferase from separate replicons.

The lux A and lux B genes of Vibrio harveyi, encoding the alpha and beta subunits of bacterial luciferase, were cloned individually into Escherichia coli in two different compatible plasmids. Active luciferase was formed in an amount equal to that produced in cells carrying a plasmid with the cloned genes on a single fragment.

DNA, Recombinant↗
PubMed2005

Systemic Agrobacterium tumefaciens-mediated transfection of viral replicons for efficient transient expression in plants.

Plant biotechnology relies on two approaches for delivery and expression of heterologous genes in plants: stable genetic transformation and transient expression using viral vectors. Although much faster, the transient route is limited by low infectivity of viral vectors carrying average-sized or large genes. We have developed constructs for the efficient delivery of RNA viral vectors as DNA precursors and show here that Agrobacterium-mediated delivery of these constructs results in gene amplification in all mature leaves of a plant simultaneously (systemic transfection). This process, called "magnifection", can be performed on a large scale and with different plant species. This technology combines advantages of three biological systems (the transfection efficiency of A. tumefaciens, the high expression yield obtained with viral vectors, and the post-translational capabilities of a plant), does not require genetic modification of plants and is faster than other existing methods.

Agrobacterium tumefaciens↗
PubMed1976

Translocation of a discrete piece of deoxyribonucleic acid carrying an amp gene between replicons in Eschericha coli.

A number of well-characterized R plasmids (R1drd 19. K1.R100-1, R46, R55-1, R64-11, R388, and R751) will mobilize an integrated amp gene from the chromosome of Escherichia coli K-12. R391 will not act in this way. The process involves recombination, and in each case the mobilizing plasmid acquires an additional piece of deoxyribonucleic acid of molecular weight 4 X 10(6). Acquisition of this deoxyribonucleic acid may impair the transfer properties of the recombinant plasmid in some cases. The process will occur in a recA background.

Ampicillin↗
PubMed1995

A DNA segment conferring stable maintenance on R6K gamma-origin core replicons.

The plasmid R6K gamma origin consists of two adjacent modules, the enhancer and the core, and requires R6K initiator protein pi for replication. While the core alone can replicate at a low level of wild-type pi protein, we show here that host cells do not stably maintain core plasmids. The presence of the enhancer segment confers stable inheritance on core plasmids without a significant change in average plasmid copy number. Deletions and site-directed mutagenesis indicated that the stability of core plasmids is not mediated by binding sites or consensus sequences in the enhancer for DnaA, pi protein, gyrase, Fis, or Dcm methylase. Proper segregation of core plasmids requires only the R6K stb or stability-related region, which includes the 20-bp segment of the 100-bp enhancer adjacent to the core. The use of the pi 116 mutant protein, which increases plasmid copy number fourfold, does not stabilize core plasmids lacking the enhancer. We also show that at an elevated level of wild-type pi, the gamma-origin plasmid is unstable, even in the presence of the enhancer. We discuss the differences and similarities between the R6K stability system and those found in other plasmids.

Bacterial Proteins↗
PubMed1997

Interactions of the RepA1 protein with its replicon targets: two opposing roles in control of plasmid replication.

By studying the interaction of derivatives of RepFIC miniplasmids, we were able to demonstrate that under certain conditions the RepA1 initiator protein inhibits plasmid replication. An analysis of cloned derivatives whose replication is inhibited by the RepA1 protein revealed the existence of two areas of the RepFIC genome that interact with RepA1 in the inhibition reaction. One of these areas, which occurs in the origin region, was explored by in vivo methylation protection footprinting studies. The protected area was 200 bp long and showed a definite periodicity of protected and hypersensitive sites, suggesting that RepA1 promotes a topological change in the RepFIC genome. The significance of our results is discussed in the context of plasmid replication control.

Bacterial Proteins↗
PubMed1972

Simian virus 40 deoxyribonucleic acid synthesis: the viral replicon.

Three temperature-sensitive (ts) mutants of simian virus 40 (SV40) in complementation group A (tsA7, tsA28, tsA30) have been isolated and characterized in permissive and restrictive host cells. At 41 C in the AH line of African green monkey kidney cells, the mutants are deficient in an early function required to produce infectious viral deoxyribonucleic acid (DNA). Temperature-shift experiments and analysis of SV40 viral DNA replication by gel electrophoresis have provided strong evidence that the ts gene product of the three mutants is directly required to initiate each new round of viral DNA replication but is not required to complete a cycle which has already begun. The synthesis of mutant DNA molecules themselves can be initiated by a nonmutant gene product in viral complementation studies at 41 C. The cell, however, cannot substitute a host function to provide the initiator required for the replication of free viral DNA. The viral initiator is also required to establish the stable transformation of 3T3 cells.

Animals↗
PubMed1974

[Replicon].

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Bacteria↗