| dc.description.abstract |
<p>In Drosophila melanogaster, where males are XY and females are XX, dosage compensation
is acheived by approximately two-fold upregulation of transcription of the single
male X chromosome. This upregulation is mediated by the dosage compensation complex
(DCC), which is assembled in a sequential manner on the male X chromosome and is composed
of the two noncoding roX (RNA on the X) RNAs and at least five proteins, including
the RNA helicase Maleless (MLE). MLE contains two highly conserved double stranded
RNA binding domains (DRBDs) at the N terminus. We investigated the roles of the roX
RNAs and MLE helicase through experiments using classical genetic methods to generate
and analyze the effects of mutants and mutant transgenes, immunolocalization experiments
to study MSL protein and roX RNA to chromosomes. For the first time in vivo, we demonstrate
that MLE associates with double stranded RNA in a sequence non-specific manner that
is independent of other DCC components. Importantly, we find that the DSRBDs of MLE
are essential for dosage compensation but are not required for MLE localization to
the male X chromosome. We propose that although the DSRBDs are not essential for
ds RNA binding, they may act synergistically with other domains of MLE or other MSLs
to associate with RNA in vivo. We propose that a MLE/ roX RNA association involving
secondary structure formed by the roX RNAs may be involved in the assembly, stabilization,
or function of the DCC.</p>
|
|
