A region containing repeated elements is associated with transcriptional termination of Leishmania infantum ribosomal RNA genes.
A novel repetitive DNA element has been isolated from the Leishmania infantum genome. The 348 bp long element, designated LiR3, was found to be located downstream from the 3'-end of the ribosomal RNA (rRNA) genes. This LiR3 element has short sequences with potential to form stem-loop structures similar to those of the bacterial rho-independent transcriptional terminators. Given both the structural features and the genomic location of this element we searched for a possible functional implication of these structures in the termination of rRNA transcription. Nuclear run-on assays indicated that indeed there is a transcriptional blockage associated with the LiR3 element. Several chi-like elements, resembling the recombination-promoting sites of Escherichia coli, were identified within the sequences associated with the stem-loop structures. A possible implication of these chi-like elements in rRNA gene conversion events is discussed.
Requena
J M
JM
Centro de Biología Molecular, Severo Ochoa, Universidad Autónoma de Madrid, Spain. jmrequena@mvax.cbm.uam.es
Soto
M
M
Quijada
L
L
Carrillo
G
G
Alonso
C
C
D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D016054:DNA, Protozoan / Q000235:genetics*; D018314:Leishmania infantum / Q000235:genetics*; D008969:Molecular Sequence Data; D012335:RNA, Ribosomal / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014158:Transcription, Genetic
D016054:DNA, Protozoan; D012335:RNA, Ribosomal