Nucleic Acids Research, 1989, Vol. 17, No. 2 631-643
© 1989
MOLECULAR BIOLOGY |
CMER, an RNA encoded by human cytomegalovirus is most likely transcribed by RNA polymerise III
hm
Institute für Biochemie der Medizinischen Fakultät, Universit
t Erlangen-Nürnberg Fahrstraße 17, D-8520 Erlangen
1lnstitut für klinische und molekulare Virologie, Universität Erlangen Nürnberg Loschgestraße 7, D-8520 Erlangen, FRG
*To Whom correspondence should be addressed
Received October 7, 1988. Revised December 20, 1988. Accepted December 20, 1988.
Through computer analysis of a human cytomegalovirus (HCMV) genomic region, previously identified to be homologous to human genoraic DNA, an element showing significant similarity to the 3'-internal control region (3'-ICR or B-block) of a eukaryotic RNA polymerase lll promoter could be detected. This region - located on the EcoRl b fragment within the UL segment of the viral genome of HCMV strain AD 169 - cannot be transcribed in vitro in an RNA polymerase lll specific transcription system. However, this part of the viral genome is able to compete for components of the RNA polymerase III transcription complex as shown in template exclusion experiments and by gel retardation assays. Two different synthetic oligonucleotides complementary to the 3'-ICR and to nucleotides located immediately downstream of this promoter element can anneal specifically to a HCMV-encoded ribonucleic acid (termed CMER) synthesized in human foreskin fibroblasts (HFF) late in virus replication. As a consequence of identifying the transcription initiation point by primer extension analyses the position of the 5'-internal control region (5'-lCR or A-block) of the CMER gene could be uncovered. Both identified control regions (the A-block as well as the B-block) of the transcription unit exhibit significant similarities to corresponding regulatory elements of other class lll genes, including virus encoded class lll genes. Initiation of in vivo transcription occurs 15 nucleotides upstream of the 5-border of the 5-lCR and the two noncontiguous gene internal promoter elements are separated by 79 nucleotides.
+Present address: University of North Carolina, Department of Biology, Charlotte, NC 28223, USA