Nucleic Acids Research, Vol 24, Issue 9 1662-1668, Copyright © 1996 by Oxford University Press
C Rovira and JE Edstrom
Cp1 is a polymorphic short interspersed repeat (SINE) which is distributed
over the whole genome of the dipteran Chironomus pallidivittatus, and is
particularly abundant in the centromeres. It contains two different
sequence modules, one of which, the B module, has a polymerase III internal
control region (ICR) typical for tRNA genes (A and B box). Such sequence
motifs are common in SINEs and assumed to function in RNA-mediated
transposition. In the present case, however, several structural features
speak for another role. An investigation of the transcription of the B
module shows that it encodes a 99 nt RNA species in vivo, Cp1-RNA,
terminating within the module. The transcription unit is likely to have
evolved from a pre- tRNA gene and the transcript has sequence similarities
to non-processed pre-tRNA. Most of the in vitro transcription is eliminated
by deletion or substitution mutation of an upstream TATA box, present
within the B module, as well as by changing either the A or B box. The
properties of the transcript suggest that it does not have a role in
transposition but may have some other function, perhaps in the centromere.
ARTICLES
Centromeric polymerase III transcription units in Chironomus pallidivittatus
Department of Genetics, Lund University, Sweden.
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