Asymmetric behavior of archaeal prolyl-tRNA synthetase.
Archaeal prolyl-tRNA synthetases differ from their bacterial counterparts: they contain an additional domain (about 70 amino acids) appended to the carboxy-terminus and lack an editing domain inserted into the class II catalytic core. Biochemical and structural approaches have generated a wealth of information on amino acid and tRNA specificities for both types of ProRSs, but have left a number of aspects unexplored. We report here that the carboxy-terminal domain of Methanocaldococcus jannaschii ProRS is not involved in tRNA binding since its deletion only mildly affects the kinetic parameters for the enzyme. We also demonstrate that M. jannaschii ProRS is a homodimeric enzyme that is functionally asymmetric; only one of the two active sites at a time is able to form prolyl-adenylate, and only one tRNA molecule binds per dimer. Together with previous reports our results show that asymmetry might be a general feature of the aminoacylation reaction catalyzed by dimeric aminoacyl-tRNA synthetases from both classes.
Ambrogelly
Alexandre
A
Department of Molecular Biophysics, Yale University, P.O. Box 208114, New Haven, CT 06520-8114, USA. alex@trna.chem.yale.edu
Kamtekar
Satwik
S
Stathopoulos
Constantinos
C
Kennedy
Dexter
D
Söll
Dieter
D
D000604:Amino Acyl-tRNA Synthetases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D019281:Dimerization; D017015:Methanococcales / Q000201:enzymology* / Q000235:genetics; D009711:Nucleotides / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism*; D017384:Sequence Deletion; D046249:Transfer RNA Aminoacylation
D019843:Archaeal Proteins; D009711:Nucleotides; D012346:RNA, Transfer, Amino Acyl; D000604:Amino Acyl-tRNA Synthetases; C100134:prolyl T RNA synthetase