title: DNA sequence alterations in Hr-t deletion mutants of polyoma virus.
abstract: We have investigated the DNA sequence alterations in several hr-t mutants of polyoma virus. These mutants are defective in one of the two known viral functions essential for transformation and are altered with respect to several minor T antigen species. The lesions in some of these mutants have been mapped previously by marker rescue experiments to Hpa II fragment 4 (Hpa II-4, 78.4--91.7 map units) in the proximal part of the early region of the viral DNA. Thirteen of sixteen hr-t mutants examined carry deletions 2 to 5 map units (100--250 bp) long in Hpa 11-4. Three mutants carry either point mutations or very small deletions/insertions. Eight of the deletion mutants were mapped closely with restriction enzymes. Seven of them have deletions located entirely within the Hae III subfragment A of Hpa II-4 (the Hae A subfragment, 78.4--85.2 map units), and one extends just beyond this subfragment, ending at 85.5 map units. The complete sequence of the wild-type Hae A subfragment was determined and compared with those of four deletion mutants, NG-18, A-8, 6B5 and B-2. The deletion in each of these mutants is out-of-phase: NG-18, 187 bp; A-8, 127 bp; 6B-5, 179 bp; B-2, 241 bp. All are expected to remove protein sequences in the C terminal part of the small t antigen.
mesh_terms: D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm / Q000235:genetics*; D001483:Base Sequence; D002472:Cell Transformation, Viral; D002872:Chromosome Deletion; D004262:DNA Restriction Enzymes; D004279:DNA, Viral / Q000235:genetics*; D005796:Genes; D005814:Genes, Viral; D009154:Mutation; D011120:Polyomavirus / Q000235:genetics*; D014764:Viral Proteins / Q000235:genetics*
chemical_list: D000951:Antigens, Neoplasm; D004279:DNA, Viral; D014764:Viral Proteins; D004262:DNA Restriction Enzymes