CHARACTERIZATION OF TRANSCRIPTION INITIATION, TRANSLATION INITIATION,AND POLY(A) ADDITION SITES IN THE GENE-SIZED MACRONUCLEAR DNA-MOLECULES OF EUPLOTES
S. Ghosh et al., CHARACTERIZATION OF TRANSCRIPTION INITIATION, TRANSLATION INITIATION,AND POLY(A) ADDITION SITES IN THE GENE-SIZED MACRONUCLEAR DNA-MOLECULES OF EUPLOTES, Nucleic acids research, 22(2), 1994, pp. 214-221
The DNA in the transcriptionally active macronucleus of the hypotricho
us ciliate Euplotes crassus exists as short, linear molecules with eac
h molecule encoding a single genetic function. Previous work has indic
ated that coding regions occupy the majority of macronuclear DNA molec
ules. In the present study we have defined the transcription initiatio
n sites and poly(A) addition sites for a number of different macronucl
ear genes in Euplotes crassus. Our results indicate that mature transc
ripts represent all but similar to 100-200 bases of the non-telomeric
sequences in macronuclear DNA molecules. We have also examined the seq
uences in the vicinity of transcription start sites, poly(A) addition
sites, and translation initiation sites for Euplotes species genes in
an attempt to define the cis-acting elements that control these proces
ses. Our results indicate that some of the common sequence elements kn
own to control these processes in higher eukaryotes are likely not uti
lized by Euplotes genes. The data do indicate the presence of other co
nserved sequences both preceding and at the site of poly(A) addition,
as well as at the site of translation initiation. These conserved sequ
ences may serve an analogous role in these organisms. Finally, we have
found that most macronuclear DNA molecules have transcription initiat
ion sites within 30 bp of the telomere, suggesting that the telomere m
ay play a role in promoting transcription.