|Budget Amount *help
¥2,200,000 (Direct Cost : ¥2,200,000)
Fiscal Year 1994 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1993 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1992 : ¥700,000 (Direct Cost : ¥700,000)
Ribosomal RNA (rRNA) is highly conserved macromolecule. Currnet evidence shows a functional role of rRNA in protein biosynthesis. However, almost nothing is known about the detailed functional structure of the rRNA and mechanism of its action in the process of protein synthesis. In 1991, we found a site-specific anti-rRNA autoantibody (anti-28S) in sera from patients with autoimmune disease. Anti-28S strongly inhibits protein synthesis at the step of interaction between elongation factors and ribosomes. In this project during three years, 1992 to 1994, we have studied on the structure and function of the antibody-binding region of rRNA using anti-28as a probe. We have reported following findings and clarified involvement of the RNA domain in interaction with elongation factors and the associated GTP hydrolysis :
(1) Anti-28S specifically protects a region termed the "GTPase domain" within 28S rRNA from RNase digestion and chemical modifications. Four bases including G-1959 were identified as elements involved in formation of the autoimmune epitope.
(2) Ribosomal proteins P1, P2, P0, and L12 bind to be GPTase domain and affect the tertiary structure of the RNA domain.
(3) Prokaryotic ribosomes shows very low accessibility to anti-28S.However, a base substitution of A-1067 to G at the position equivalent to eukaryotic 1959 site causes high anti-28S accessibility of the ribosomes, indicating G-1959 is important for ansi-28S recognition.
(4) G-1959 is also protected by elongation factor EF-2 from chmical modification with dimethy1 sulfate, suggesting that anti-28S directly blocks the EF-2 action to the GTPase domain.
(5) Anti-28S activity is detected in sera from 17 % patients with SLE.All the anti-28S sera also contain anti-P antibody reactive with tha domain-associating proteins P1, P2, and P0.