Non-glucosylated T4 DNA was digested with R.EcoRI and the resulting fragments covalently joined to lambda vectors. The genetic content of each lambda-T4 hybrid was determined by marker-rescue tests. The isolation of many recombinants containing partial-digestion products of T4 DNA provided the overlapping sequences necessary to order fragments within the T4 genome. The present analyses include parts of the "early" region between genes 42 and 46, and much of the "late" region between genes 50 and 29. T4 cytosine-DNA digested to completion by R.EcoRI was used to identify the fragments of DNA within the lambda-T4 recombinants. The T4 cytosine-DNA was also sensitive to R.HindIII and R.Xho but not to R.BamH1.

EMBL accession no. X14869 The nucleotide sequence of the region of bacteriophage T4 inh(lip)-hoc genes (108700-111800 bp of the T4 DNA length (1)) was determined. Cloning and analysis of this region were described in (2). Three open reading frames (ORFs) coding for the polypeptides of 97, 205 and X amino acids (aa) were found by computer analysis in the DNA r-strand, the ORF X being a part of the ORF which goes beyond the sequenced region. Two ORFs corresponding by their lengths to the 226aa and 376aa polypeptides were found in the DNA 1-strand. By the amino acid content as well as the molecular mass the protein coded by the ORF 376aa corresponds to the hoc gene product (3). Two potential promoters, P1 (2031-2061) and P2 (2086-2056), transcription from which is directed to the opposite sides and which are located in the different DNA strands, were found in this region. Both promoters are typical of the promoter-consensus DNA structure of bacteriophage T4 late promoters (4). The potential transcription terminator (192-209) is located after the suggested bacteriophage T4 hoc gene (ORF 376aa).

No abstract

The plasmid designated pAD1 was isolated from the cells of four variants of Bacillus brevis var. G.-B. The plasmid DNA has a molecular weight of about 47.1 x 10(6) daltons and contains 43.4 mole % G+C. The bulk of pAD1 DNA (96--98%) is associated with the fraction of chromosome DNA and membranes. Restriction endonucleases Sma I, Sal I and Bam HI cleaved the plasmid DNA into two, two and six fragments, respectively. The cleavage map of the pAD1 genome has been constructed for these three endonucleases. Restriction enzymes Eco RI, Hind III, Kpn I and Pst I hydrolized the plasmid DNA into 16, 21, 10 and 9 fragments, respectively. The presence of repeated sequences in the plasmid genome was shown based on pAD1 DNA cleavage by these endonucleases.

In vitro repair of single strand breaks in T4 and phage DNA caused by 32p decay was studied. Zone centrifugation procedure showed that polynucleotide kinase, ligase enzyme system failed to repair 32P-damages. It was found that damaged DNA contained gaps and could be repaired by DNA-polymerase I, polynucleotide ligase treatment.