A 2ND CLASS OF SYNTHETASE STRUCTURE REVEALED BY X-RAY-ANALYSIS OF ESCHERICHIA-COLI SERYL-TRANSFER RNA-SYNTHETASE AT 2.5-A

The three-dimensional crystal structure of seryl-transfer RNA synthetase from Escherichia coli, refined at 2.5 Å resolution, is described. It has an N-terminal domain that forms an antiparallel α helical coiled-coil, stretching 60 Å out into the solvent and stabilized by interhelical hydrophobic interactions and an active-site α - β domain based around a seven-stranded antiparallel β sheet. Unlike the three other known synthetase structures, the enzyme contains no classical nucleotide-binding fold, and is the first representative of a second class of aminoacyl-tRNA synthetase structures. © 1990 Nature Publishing Group.