Summary of Research Project Results under JSPS FY2001
"Research for the Future Program"

1.Research Institution Chiba Institute of Technology
2.Research Area Life Sciences
3.Research Field Structure and Functional Control Mechanism of Biomolecules (Structural Biology and Functional Molecules)
4.Term of Project FY 1997 〜 FY 2001
5.Project Number 97L00503
6.Title of Project Structural Biology of RNA

7.Project Leader
Name Institution,Department Title of Position
Gota Kawai Chiba Institute of Technology, Department of Industrial Chemistry Associate Professor

8.Core Members

Names Institution,Department Title of Position
Yutaka Muto The University of Tokyo, Graduate School of Sciences Lecturer
Akio Takenaka Tokyo Institute of Technology, Graduate School of Bioscience and Biotechnology Associate Professor

9.Summary of Research Results

(1)Structure determination of RNA by NMR -- Structures of a 39-mer RNA corresponding to the dimerization initiation site of HIV-1 genomic RNA were determined in two types of conformations; kissing dimer and duplex dime. It was found that the two conformations are almost identical except for the region around the both ends of the self complement loop. Structure of a 29-mer RNA corresponding to the helix 6 of human SRP RNA was determined in the free hairpin form. The GGAG tetraloop in helix 6 adopts a similar conformation to that of GNRA tetraloop, suggesting that these tetraloops are included in an extensive new motif GNRR. Compared with the structure of helix 6 in complex with SRP19 determined previously, the GGAG tetraloop in the complex adopts a similar conformation to that of the free form, although the conformation is changed to a more open conformation upon SRP19 binding. NMR analysis of a 31-mer RNA corresponding a pseudoknot, PK1, of tmRNA revealed that the PK1 RNA is folded into a pseudoknot structure in the presence of Mg2+. Results of NMR analyses of PK1 mutants together with their biological activities indicates that trans-translation requires the pseudoknot structure stabilized by Mg2+ and specific residues G61 and G62 in loop 3. Structure of a 22-mer RNA corresponding to the P7/P9.0 region and the 3'-terminal guanosine of the Tetrahymena group I intron was also determined to find a new structural motif, BT-motif. (2) Structure determination of RNA by X-ray crystallography --Single crystals for RNAs corresponding to the dimerization initiation site of HIV-1 genomic RNA and the hammerhead ribozyme in a heterodimer form are finally obtained. Structure determinations are in progress. (3) RNA binding proteins -- RNA recognition mechanisms were revealed for the Drosophila Sxl protein and human U2AF protein by X-ray crystallography and NMR technique.

10.Key Words

(1)RNA、(2)tertiary structure、(3)NMR
(4)X-ray crystallography、(5)RNA-binding protein、(6)RNA-protein interaction
(7)two-step dimerization、(8)SRP RNA、(9)tmRNA