Small Nucleolar RNAs and Pre-rRNA Processing in Plants

Small nucleolar RNAs and pre-rRNA processing in plants.

Messenger RNA (mRNA) translation and thereby gene expression depend on the cell’s ability to produce vast numbers of ribosomes, the major component of the translational machinery. The complexity inherent in the production of ribosomal RNAs (rRNAs), the key RNA components of the ribosome, is interesting in itself. Add to this the complex nature of the production and regulation of the myriad othe...

Processing of the precursors to small nucleolar RNAs and rRNAs

Arabidopsis small nucleolar RNA monitors the efficient pre-rRNA processing during ribosome biogenesis.

Ribosome production in eukaryotes requires the complex and precise coordination of several hundred assembly factors, including many small nucleolar RNAs (snoRNAs). However, at present, the distinct role of key snoRNAs in ribosome biogenesis remains poorly understood in higher plants. Here we report that a previously uncharacterized C (RUGAUGA)/D (CUGA) type snoRNA, HIDDEN TREASURE 2 (HID2), act...

Base pairing between U3 small nucleolar RNA and the 5' end of 18S rRNA is required for pre-rRNA processing.

The loop of a stem structure close to the 5' end of the 18S rRNA is complementary to the box A region of the U3 small nucleolar RNA (snoRNA). Substitution of the 18S loop nucleotides inhibited pre-rRNA cleavage at site A(1), the 5' end of the 18S rRNA, and at site A(2), located 1.9 kb away in internal transcribed spacer 1. This inhibition was largely suppressed by a compensatory mutation in U3,...

Dual function of C/D box small nucleolar RNAs in rRNA modification and alternative pre-mRNA splicing.

C/D box small nucleolar RNAs (SNORDs) are small noncoding RNAs, and their best-understood function is to target the methyltransferase fibrillarin to rRNA (for example, SNORD27 performs 2'-O-methylation of A27 in 18S rRNA). Unexpectedly, we found a subset of SNORDs, including SNORD27, in soluble nuclear extract made under native conditions, where fibrillarin was not detected, indicating that a f...