A restriction map of cauliflower mosaic virus DNA (strain PV 147). Mapping of the cleavage sites of HhaI, SacI, AvaI, PvuII, PstI, XbaI, EcoRI, Bg/II, HincII, HpaII and HindII + III

Isolation and Mapping of Small Cauliflower Mosaic Virus DNA Fragments Active as Promoters in Escherichia coli

Small EcoRI(*) fragments of cauliflower mosiac virus DNA (strain CM4-184), which act as promoters for the tetracycline resistance gene on the promoter probe plasmid pBRH4 in Escherichia coli, have been isolated and mapped on the viral genome. Two regions of the viral genome contain DNA sequences with promoter activity in E. coli. Two independent cloned fragments from one region direct a high level of tetracycline resistance (up to 38 mug of tetracycline per ml). Two independent fragments from the second region of the viral genome also direct tetracycline resistance, but at lower levels. The activity of the two fragments with the strongest promoter activity in E. coli may direct transcription of the viral genome in a clockwise direction. This is consistent with the direction of transcription predicted from sequence analysis of the viral DNA (Franck et al., Cell 21: 285-294, 1980). One of these fragments maps at the start of a large open translational reading frame which is predicted to contain the coding sequence for the viral coat protein. Each promoter-active fragment is located in the 5'-terminal portion of one of the six open reading frames predicted from the DNA sequence.

Physical maps of the genomes of dahlia mosaic virus and mirabilis mosaic virus-two members of the caulimovirus group

The nucleic acids of dahlia mosaic virus (DaMV) and mirabilis mosaic virus (MMV) have been isolated and compared with the native DNA of cauliflower mosaic virus (CaMV). The native DNAs of these viruses separated into circular and linear molecules during gel electrophoresis to produce patterns nearly identical to those of CaMV. The DNAS of DaMV and MMV were cloned in bacteria and used for mapping the cleavage sites for 14 different restriction endonucleases. These sites were confirmed with native viral DNA. The S1 nuclease cleavage sites and the sizes of single-stranded denaturation products of the native DNA of each virus was used to determine the location of the four single-stranded interruptions present in each virus. The largest denaturation fragment of each virus migrated in gels at about the same rate as the a strand (which has one discontinuity) of CaMV. These features have been used to construct physical maps of the viral genomes.

Isolation and characterization of faithful and altered clones of the genomes of cauliflower mosaic virus isolates Cabb B-JI, CM4-184, and Bari I

Full-length genomes of cauliflower mosaic virus (CaMV) isolates Cabb B-JI, CM4-184, and Bari I have been cloned in the SalGI site of plasmid pAT 153. The cloned DNAs were characterized by restriction mapping and infectivity assays. All the sites present in the virion DNAs were found in the cloned DNAs. Comparison of restriction maps with those of DNA from two other isolates which have been recently completely sequenced revealed a close relationship among the different isolates. Some of the clones appear to be faithful copies of the viral genomes and these viral inserts are infectious when inoculated into turnip plants. Various clones with deletions in the CaMV DNA have been isolated and characterized. Some of them may correspond to deletions naturally occurring in a subpopulation of the virus whereas others occurred during cloning. None of the deleted fragments are infectious when inoculated into plants. Strikingly, all the deletions overlap one or two of the specific single-stranded breaks characteristic of caulimoviruses, suggesting that sequences surrounding the breaks are not dispensable.

The complete nucleotide sequence of an infectious clone of cauliflower mosaic virus by M13mp7 shotgun sequencing

We have determined the complete primary structure (8031 base pairs) of an infectious clone of cauliflower mosaic virus strain CM1841. The sequence was obtained using the strategy of cloning shotgun restriction fragments in the sequencing vector M13mp7. Comparison of the CM1841 sequence with that published for another caMV strain (Strasbourg) reveals 4.4% changes, mostly nucleotide substitutions with a few small insertions and deletions. The six open reading frames in the sequence of the Strasbourg isolate are also present in CM1841.

Restriction map of native and cloned cauliflower mosaic virus DNA

Cloned CaMV DNA replicates faithfully in Escherichia coli, since the restriction map of the cloned DNA can be superimposed over that of the native viral DNA. However, some short fragments were difficult to detect in the restricted native viral DNA, whereas they formed clear bands when derived from cauliflower mosaic virus (CaMV) DNA clones propagated in the E. coli host. Apparently, the small fragments that carry variable-length single-stranded gaps present only in native viral DNA, give rise to diffuse weak bands difficult to recognize in gels. Comparison of maps for several CaMV strains permits evaluation of their possible evolutionary relationship.

Nucleotide sequence of cauliflower mosaic virus DNA

The complete nucleotide sequence (8024 nucleotides) of the circular double-stranded DNA of cauliflower mosaic virus has been established. The DNA molecule is known to possess three discrete single-stranded discontinuities, often referred to as "gaps," two in one strand and one in the other. The sequence data indicate that gap 1, the single discontinuity in the alpha strand, corresponds to the absence of no more than one or two nucleotides with respect to the complementary beta strand. The two discontinuities in the beta strand, however, are not authentic gaps since no nucleotides are missing, but are instead regions of sequence overlap: a short sequence (19 residues for gap 2, t least 2 residues for gap 3) at one terminus of each discontinuity, probably the 5' terminus, is displaced from the double helix by an identical sequence at the other boundary of the discontinuity. Analysis of the distribution of nonsense codons in the DNA sequence is consistent with other evidence that only the alpha strand is transcribed. The coding region extends around the circular molecule from 4 map units of gap 1, the map origin, to map position 91, and consists of six long open reading frames. Our findings suggest, but do not prove, that the DNA sequence of the open reading frames is colinear with viral protein sequences. The cistron for the viral coat protein, which is probably synthesized in the form of a precursor, has been situated in coding region IV on the basis of its unusual amino acid composition.