Sequences at the capped 5'-ends of polyoma virus late region mRNAs: an example of extreme terminal heterogeneity.
We have localized with respect to the genomic DNA sequence the capped 5'-termini of polyoma virus late region mRNAs. A minimum of fifteen different purine termini were found within a 94 base pair region (66.36 to 68.12 map units, nt 5075-5168) immediately preceding the sequence determining the late region mRNA leader repeat (1-3). The most common termini occur at nearly every possible purine within a 25 bp sequence proximal to the leader repeat unit. These do not bear the usual positional relationship to a sequence resembling the 'TATA' box consensus. Deletion mutants lacking minor cap sites and sequences upstream from the principal cap sites were viable. A deletion mutant lacking one of the principal cap sites formed small plaques, while a slightly larger deletion further impinging on the principal cap site region was non-viable. The principal cap sites, which we assume to be transcriptional initiation points, are included in a DNaseI hypersensitive region of polyoma virus chromatin (4).
D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D002460:Cell Line; D002472:Cell Transformation, Viral; D051379:Mice; D009693:Nucleic Acid Hybridization; D009843:Oligoribonucleotides / Q000032:analysis; D011120:Polyomavirus / Q000235:genetics*; D012315:RNA Caps / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics*; D006163:Ribonuclease T1
D009843:Oligoribonucleotides; D012315:RNA Caps; D012333:RNA, Messenger; D012367:RNA, Viral; D006163:Ribonuclease T1