ANALYSIS OF THE TRANSCRIPTION PATTERN OF HSV-1 UL52 AND UL53 GENES

The UL52 and UL53 genes of herpes simplex virus type-1 are both locate d in the BamHI-L DNA fragment, with an overlap of 14 amino acids. An R Nase protection experiment was designed to determine the 5' termini of both the UL52 and UL53 mRNAs. The 5' end of the UL52 mRNA was found t o be located 100 bp upstream of its ATG initiation codon. Surprisingly , the 5' terminus of the UL53 gene was found to be downstream of its p utative initiation codon. Therefore, it was suggested that the transla tion of the UL53 open reading frame (ORF) starts at an internal initia tion codon that is located 55 codons downstream of the putative one. A hybrid selection experiment was performed in which the UL53-specific mRNA was selected from BSC-1 cells infected with HSV-1 KOS and transla ted in vitro. The translation product of the UL53 message was found to be 32 kD (shorter than the original 37.5 kD ORF). The size of the pro tein obtained corresponds with the expected translation product starti ng at the downstream initiation codon. Analysis of the sequence upstre am of this initiation codon reveals the presence of a promotor sequenc e. Therefore, we suggest that the UL53 protein is 54 amino acids short er than was previously suggested and is located at coordinates 112,341 -113,193.