Unconventional processing of the 3' termini of the Epstein-Barr virus DNA polymerase mRNA.
Northern blot analysis of the Epstein-Barr virus DNA polymerase mRNA identified two discrete sizes of virally encoded polymerase transcripts, 5.08 kb detected in strains P3HR1, Raji, W-91, and FF-41 and 3.7 kb detected solely in the prototype B95-8 strain. 3' S1-nuclease mapping and analysis of cDNA sequence generated by RNA-based PCR demonstrated that the 3.7-kb polymerase mRNA from B95-8 terminates 484 base pairs downstream of the open reading frame in a region of the genome remarkable for its lack of an apparent polyadenylylation signal. Moreover, between the cleavage point and the poly(A) tract of the cDNAs are a series of inserted nucleotides, mostly adenosine and uridine residues of unknown origin. A similar analysis of the 3' terminus of the 5.0-kb mRNA from the other cell lines revealed that polyadenylylation occurs 1.4 kb downstream of the B95-8 terminus. This region is deleted in B95-8, which accounts for the alternate upstream terminus used in B95-8. Like the 3.7-kb terminus, the 5.0-kb terminus lacks a canonical polyadenylylation signal, but contains a rarely used UAUAAA sequence 32 bp upstream of the poly(A) tail. These results indicate that the mRNA encoded by the Epstein-Barr virus DNA polymerase gene is polyadenylylated at two different termini without the use of canonical signals, raising the possibility of involvement of a virus-encoded factor in 3' processing of this message.
Furnari
F B
FB
Department of Microbiology, University of North Carolina, Chapel Hill 27599.
Adams
M D
MD
Pagano
J S
JS
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D004259:DNA-Directed DNA Polymerase / Q000235:genetics*; D016679:Genome, Viral; D004854:Herpesvirus 4, Human / Q000201:enzymology / Q000235:genetics*; D008214:Lymphocytes / Q000166:cytology; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000378:metabolism; D011061:Poly A / Q000096:biosynthesis*; D016133:Polymerase Chain Reaction; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000096:biosynthesis*; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
D009711:Nucleotides; D012333:RNA, Messenger; D011061:Poly A; D004259:DNA-Directed DNA Polymerase