Involvement of 18S and 25S rRNA in translational fidelity and catalytic activity of yeast ribosomes

• Published in: The FASEB journal Vol. 21; no. 5; p. A280
• Main Authors: Synetos, Dennis, Konstantinidis, Theodoros C., Tselika, Smaragdi, Panopoulos, Panagiotis, Dresios, John
• Format: Journal Article
• Language: English
• Published: Federation of American Societies for Experimental Biology 01-04-2007
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.21.5.A280-a

Accurate and efficient translation of mRNA is a critical step in protein synthesis. The decoding and peptidyltransferase (PTase) centers are mainly RNA machines. Helices 18, 27, 34 and 44 of yeast 18S rRNA participate in decoding. In h44, A1491G (E. coli numbering), which restores a C1409‐G1491 base pair as in E. coli, and U1495C, a hygromycin‐resistant mutation, affected decoding. A1491G mutants were sensitive to the misreading and killing effects of the antibiotic paromomycin (PM), while U1495C mutants were resistant to both. Further, G886A, G888A and U912C in h27 increased translational fidelity and resistance to PM, while double mutation U912C‐G888A increased fidelity additively but became highly sensitive to PM. Another mutation, G517A in h18, caused strong antisuppression and resistance to PM, versus suppression in E. coli. Site C1054 of h34 was crucial since different substitutions caused opposite effects, i.e. suppression/infidelity in C1054A or antisuppression/enhanced fidelity in C1054U. Moreover, C1054A, but not C1054U, decreased PTase activity. Mutation C2658U in the sarcin/ricin domain of yeast 25S rRNA lowered PTase activity; it also affected the 40S function and separated the killing and misreading effects of PM. Thus, the ribosomal subunits interact to optimize translational fidelity and PTase activity.
Supported by the “Karatheodori 2004” Research Program of Patras University, Greece