Methanocaldococcus jannaschii prolyl-tRNA synthetase charges tRNA(Pro) with cysteine.
Methanocaldococcus jannaschii prolyl-tRNA synthetase (ProRS) was previously reported to also catalyze the synthesis of cysteinyl-tRNA(Cys) (Cys-tRNA(Cys)) to make up for the absence of the canonical cysteinyl-tRNA synthetase in this organism (Stathopoulos, C., Li, T., Longman, R., Vothknecht, U. C., Becker, H., Ibba, M., and Söll, D. (2000) Science 287, 479-482; Lipman, R. S., Sowers, K. R., and Hou, Y. M. (2000) Biochemistry 39, 7792-7798). Here we show by acid urea gel electrophoresis that pure heterologously expressed recombinant M. jannaschii ProRS misaminoacylates M. jannaschii tRNA(Pro) with cysteine. The enzyme is unable to aminoacylate purified mature M. jannaschii tRNA(Cys) with cysteine in contrast to facile aminoacylation of the same tRNA with cysteine by Methanococcus maripaludis cysteinyl-tRNA synthetase. Although M. jannaschii ProRS catalyzes the synthesis of Cys-tRNA(Pro) readily, the enzyme is unable to edit this misaminoacylated tRNA. We discuss the implications of these results on the in vivo activity of the M. jannaschii ProRS and on the nature of the enzyme involved in the synthesis of Cys-tRNA(Cys) in M. jannaschii.
Ambrogelly
Alexandre
A
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, USA.
Ahel
Ivan
I
Polycarpo
Carla
C
Bunjun-Srihari
Shipra
S
Krett
Bethany
B
Jacquin-Becker
Clarisse
C
Ruan
Benfang
B
Köhrer
Caroline
C
Stathopoulos
Constantinos
C
RajBhandary
Uttam L
UL
Söll
Dieter
D
D000215:Acylation; D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism*; D002384:Catalysis; D003545:Cysteine / Q000378:metabolism*; D017016:Methanococcaceae / Q000201:enzymology*; D017393:RNA Editing
D000604:Amino Acyl-tRNA Synthetases; C100134:prolyl T RNA synthetase; D003545:Cysteine