Human transaldolase-associated repetitive elements are transcribed by RNA polymerase III.
Repetitive elements flanked by exons 2 and 3 of the human transaldolase gene, thus termed transaldolase-associated repetitive elements, TARE, were identified in human DNA. Nonpolyadenylated TARE transcripts were detected by Northern blot analysis and cloned by reverse transcriptase-mediated polymerase chain reaction from human T lymphocytes. A dominant 1085-nucleotide long transcript, TARE-6, contained two adjacent Alu elements, a right monomer and a complete dimer, oriented opposite to the direction of transcription of the transaldolase gene. Reverse transcriptase-polymerase chain reaction and in vitro transcription analyses showed that transcription of TARE-6 proceeded in the orientation of the RNA pol III promoter of the Alu dimer and opposite to the orientation of the TAL-H gene. TAREs lacking RNA polymerase III promoter showed no transcriptional activity. In vitro transcription of TARE-6 was resistant to 1 microg/ml alpha-amanitin but sensitive to 100 microg/ml alpha-amanitin and tagetitoxin, suggesting involvement of RNA polymerase III. TAREs in both the transaldolase and HSAG-1 genomic loci were surrounded by TA target site duplications. Homologies between transaldolase and HSAG-1 break off internally at splice donor and acceptor sites. The results suggest RNA polymerase III-mediated transcription of TARE may be a source of repetitive elements, contributing to distinct genes and thus shaping the human genome.
Perl
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A
Departments of Medicine, Microbiology and Immunology, and Pathology, State University of New York Health Science Center, College of Medicine, Syracuse, New York 13210, USA. perla@vax.cs.hscsyr.edu
Colombo
E
E
Samoilova
E
E
Butler
M C
MC
Banki
K
K
D001483:Base Sequence; D003001:Cloning, Molecular; D005091:Exons; D006801:Humans; D008969:Molecular Sequence Data; D012320:RNA Polymerase III / Q000378:metabolism*; D012091:Repetitive Sequences, Nucleic Acid; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D014153:Transaldolase / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D014158:Transcription, Genetic
D014153:Transaldolase; D012320:RNA Polymerase III