Ribosomal shunting mediated by a translational enhancer element that base pairs to 18S rRNA.

Proc Natl Acad Sci U S A 2006 Jun 12;103(25):9488-93. Epub 2006 Jun 12.

Department of Neurobiology, The Scripps Research Institute, and The Skaggs Institute for Chemical Biology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.

In eukaryotes, 40S ribosomal subunits move from their recruitment site on the mRNA to the initiation codon by an as yet poorly understood process. One postulated mechanism involves ribosomal shunting, in which ribosomal subunits completely bypass regions of the 5' leader. For some mRNAs, shunting has been shown to require various mRNA elements, some of which are thought to base pair to 18S rRNA; however, the role of base pairing has not yet been tested directly. In earlier studies, we demonstrated that a short mRNA element in the 5' leader of the Gtx homeodomain mRNA functioned as a ribosomal recruitment site by base pairing to the 18S rRNA. Using a model system to assess translation in transfected cells, we now show that this intermolecular interaction also facilitates ribosomal shunting across two types of obstacles: an upstream AUG codon in excellent context or a stable hairpin structure. Highly efficient shunting occurred when multiple Gtx elements were present upstream of the obstacles, and a single Gtx element was present downstream. Shunting was less efficient, however, when the multiple Gtx elements were present only upstream of the obstacles. In addition, control experiments with mRNAs lacking the upstream elements showed that these results could not be attributed to recruitment by the single downstream element. Experiments in yeast in which the mRNA elements and 18S rRNA sequences were both mutated indicated that shunting required an intact complementary match. The data obtained by this model system provide direct evidence that ribosomal shunting can be mediated by mRNA-rRNA base pairing, a finding that may have general implications for mechanisms of ribosome movement.

Download full-text PDF

Source
http://dx.doi.org/10.1073/pnas.0603597103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1480434PMC
June 2006
2 Reads

Publication Analysis

Top Keywords

ribosomal shunting
16
18s rrna
16
base pairing
12
recruitment site
8
mrna elements
8
gtx elements
8
upstream obstacles
8
elements upstream
8
model system
8
multiple gtx
8
ribosomal subunits
8
shunting mediated
8
shunting
7
ribosomal
7
mrna
5
elements
5
base
5
hairpin structure
4
structure highly
4
context stable
4

References

(Supplied by CrossRef)

Kapp et al.
Annual review of biochemistry 2004

Journal of Biological Chemistry 2005

Templeton et al.
Nature structural & molecular biology 2006

Pisarev et al.
Comptes rendus biologies 2005

Kozak et al.
Gene 2002

Xi et al.
Genes & Development 2004

PNAS 2004

Ryabova et al.
Progress in nucleic acid research and molecular biology 2002

Yueh et al.
Genes & Development 2000

Mignone et al.
Applied bioinformatics 2002

Mauro et al.
PNAS 1997

Similar Publications