Initiation of adenovirus DNA replication

Restriction maps of human adenovirus types 2, 5, and 3 for BstEII, MluI, NdeI, NruI and SfiI endonucleases

The positions of cleavage sites for BstEII, MluI, NdeI, NruI and SfiI restriction endonucleases in the DNA from human adenovirus (Ad) serotypes 2, 5 and 3 were determined. In addition, the sites of cleavage for BglII in Ad3 DNA were located. All these enzymes possess a narrow specificity and generated a small number of discrete DNA fragments. Ad3 DNA was not cleaved by MluI and SfiI. It was the first observation of the absence of cleavage of an adenovirus DNA by a restriction endonuclease.

Replication of adenovirus mini-chromosomes

We have isolated adenovirus origins of DNA replication from both the right and left ends of the genome, which are functional on linear autonomously replicating mini-chromosomes. The mini-chromosomes contain two cloned inverted adenovirus termini and require non-defective adenovirus as a helper. Replicated molecules are covalently attached to protein, and DNA synthesis is initiated at the correct nucleotide even when the origins are not located at molecular ends. The activity of embedded origins leads to the generation of linear mini-chromosomes from circular or linear molecules. These observations therefore suggest that sequences within the adenovirus origin of replication position the protein priming event at the adenovirus terminus. Experiments investigating the regeneration of deleted viral inverted terminal repeat sequences show a sequence-independent requirement for inverted sequences in this process. This result strongly suggests that repair results from the formation of a panhandle structure by a displaced single strand. On the basis of these observations we propose a model for the generation of adenovirus mini-chromosomes from larger molecules.

Restriction maps of human adenovirus types 2, 5 and 3 for BclI, ClaI, pvul and SphI endonucleases

The sites of cleavage by BclI, ClaI, PvuI and SphI in the DNA from adenovirus (Ad) serotypes 2, 5 and 3 have been located. Certain site coordinates were in accord with nucleotide sequences already published. A small difference in size between the PvuI-E fragments from Ad2 and Ad5 confirmed the existence of a deletion in the N-terminal moiety of Ad5 hexon gene, as previously implied by interserotypic recombinants (Boursnell and Mautner, Virology 112 (1981) 198-209) and more recently by amino acid sequencing (Von Bahr-Lindström et al., Virology 118 (1982) 352-362).

Nucleotide sequence of the early genes 3 and 4 of bacteriophage phi 29

The nucleotide sequence of an early region of the phi 29 genome has been determined. The sequenced region includes genes 3 and 4, which code for the protein covalently linked to the 5' ends of phi 29 DNA and the protein involved in the control of late transcription, respectively. The position and nature of the mutations of mutants sus3(91) and sus4(56) has also been determined.

Nucleotide sequence at the termini of the DNA of Bacillus subtilis phage phi 29

Phage phi 29 DNA cannot be phosphorylated with polynucleotide kinase and [gamma-32P]ATP because of the presence of a viral protein covalently linked to the 5' termini. The 5' ends can, however, be made susceptible to phosphorylation by treatment with alkali and alkaline phosphatase. Restriction fragments Hpa II C and Hpa II F, corresponding to the right and left ends of phi 29 DNA, respectively, were labeled at the 5' ends with polynucleotide kinase and [gamma-32P]ATP or at the 3' ends with terminal transferase and [alpha-32P]ATP or [alpha-32P]cordycepin 5'-triphosphate. After a secondary cleavage of the labeled fragments, the sequence of the first 150-180 nucleotides at the termini of phi 29 DNA was determined by the method of Maxam and Gilbert. The ends of phi 29 DNA are flush, and a six-nucleotides-long inverted terminal repetition was found. The functional implications of the sequences determined are discussed.