Nucleic Acids Research, 1989, Vol. 17, No. 2 755-766
© 1989
MOLECULAR BIOLOGY |
The modulatory element TNNCT affects transcription of a Drosophila tRNA4al gene without affecting transcription complex stability
Department of Medical Genetics and Microbiology, University of British Columbia Vancouver, BC V6T 1W5, Canada 1Program in Genetics, University of British Columbia Vancouver, BC V6T 1W5, Canada
*To whom correspondence should be addressed
Received July 25, 1988. Revised November 28, 1988. Accepted November 28, 1988.
We have previously identified a sequence of the general form TNNCT in the 5'-flanking region of a Drosophila melanogaster tRNA4al gene which positively modulates in vitro transcription. The pentadeoxynucleotide is also present in the 5'-flank of other Drosophila tRNA genes which direct transcription efficiently in vitro. We have examined transcription of a mutant of this gene further to understand the role of the TNNCT sequence. When template competition experiments were carried out, a template which contained mutations in TNNCT was a better competitor than was the wildtype template. The time-course of transcription and the effects of temperature and ionic strength on transcription indicated that mutating the TNNCT did not alter the efficiency of stable complex formation. It is proposed that the pentadeoxynucleotide TNNCT may influence the rate of transcription initiation by RNA polymerase III bound to transcription complexes.
+Present address: Biology Department, University of California, San Diego, La Jolla, CA, USA