Previous Article | Next Article ![]()
Mol. Cell. Biol., 03 1997, 1354-1365, Vol 17, No. 3
PL Weaver, C Sun and TH Chang
In Saccharomyces cerevisiae, ribosomal biogenesis takes place primarily in
the nucleolus, in which a single 35S precursor rRNA (pre-rRNA) is first
transcribed and sequentially processed into 25S, 5.8S, and 18S mature
rRNAs, leading to the formation of the 40S and 60S ribosomal subunits.
Although many components involved in this process have been identified, our
understanding of this important cellular process remains limited. Here we
report that one of the evolutionarily conserved DEAD-box protein genes in
yeast, DBP3, is required for optimal ribosomal biogenesis. DBP3 encodes a
putative RNA helicase, Dbp3p, of 523 amino acids in length, which bears a
highly charged amino terminus consisting of 10 tandem lysine-lysine-X
repeats ([KKX] repeats). Disruption of DBP3 is not lethal but yields a
slow-growth phenotype. This genetic depletion of Dbp3p results in a
deficiency of 60S ribosomal subunits and a delayed synthesis of the mature
25S rRNA, which is caused by a prominent kinetic delay in pre-rRNA
processing at site A3 and to a lesser extent at sites A2 and A0. These data
suggest that Dbp3p may directly or indirectly facilitate RNase MRP cleavage
at site A3. The direct involvement of Dbp3p in ribosomal biogenesis is
supported by the finding that Dbp3p is localized predominantly in the
nucleolus. In addition, we show that the [KKX] repeats are dispensable for
Dbp3p's function in ribosomal biogenesis but are required for its proper
localization. The [KKX] repeats thus represent a novel signaling motif for
nuclear localization and/or retention.
Copyright © 1997, American Society for Microbiology
Dbp3p, a putative RNA helicase in Saccharomyces cerevisiae, is required for efficient pre-rRNA processing predominantly at site A3
Department of Molecular Genetics, The Ohio State University, Columbus 43210, USA.
This article has been cited by other articles:
Copyright © 2009 by the American Society for Microbiology. For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»