REPRODUCING THE 3-DIMENSIONAL STRUCTURE OF A TRANSFER-RNA MOLECULE FROM STRUCTURAL CONSTRAINTS

The three-dimensional structure of yeast tRNA(Phe) was reproduced at a tomic resolution with the automated RNA modeling program MC-SYM, which is based on a constraint-satisfaction algorithm. Structural constrain ts used in the modeling were derived from the secondary structure, fou r tertiary base pairs, and other information available prior to the de termination of the x-ray crystal structure of the tRNA. The program ge nerated 26 solutions (models), all of which had the familiar ''L'' for m of tRNA and root-mean-square deviations from the crystal structure i n the range of 3.1-3.8 angstrom. The interaction between uridine-8 and adenosine-14 was crucial in the modelling procedure, since only this among the tertiary pairs is necessary and sufficient to reproduce the L form of tRNA. Other tertiary interactions were critical in reducing the number of solutions proposed by the program.