Aminoacyl-tRNA formation in the extreme thermophile Thermus thermophilus.
Thermophilic organisms must be capable of accurate translation at temperatures in which the individual components of the translation machinery and also specific amino acids are particularly sensitive. Thermus thermophilus is a good model organism for studies of thermophilic translation because many of the components in this process have undergone structural and biochemical characterization. We have focused on the pathways of aminoacyl-tRNA synthesis for glutamine, asparagine, proline, and cysteine. We show that the T. thermophilus prolyl-tRNA synthetase (ProRS) exhibits cysteinyl-tRNA synthetase (CysRS) activity although the organism also encodes a canonical CysRS. The ProRS requires tRNA for cysteine activation, as is known for the characterized archaeal prolyl-cysteinyl-tRNA synthetase (ProCysRS) enzymes. The heterotrimeric T. thermophilus aspartyl-tRNA(Asn) amidotransferase can form Gln-tRNA in addition to Asn-tRNA: however, a 13-amino-acid C-terminal truncation of the holoenzyme A subunit is deficient in both activities when assayed with homologous substrates. A survey of codon usage in completed prokaryotic genomes identified a higher Glu:Gln ratio in proteins of thermophiles compared to mesophiles.
Feng
Liang
L
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8114, USA.
Stathopoulos
Constantinos
C
Ahel
Ivan
I
Mitra
Anusri
A
Tumbula-Hansen
Debra
D
Hartsch
Thomas
T
Söll
Dieter
D
D000604:Amino Acyl-tRNA Synthetases / Q000378:metabolism; D001226:Aspartate-tRNA Ligase; D001483:Base Sequence; D003062:Codon / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D019884:Nitrogenous Group Transferases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000096:biosynthesis*; D012346:RNA, Transfer, Amino Acyl / Q000096:biosynthesis*; D017384:Sequence Deletion; D013696:Temperature; D016963:Thermus thermophilus / Q000235:genetics / Q000378:metabolism*
D003062:Codon; D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012346:RNA, Transfer, Amino Acyl; C412016:Asp-tRNA(Asn) amidotransferase; D019884:Nitrogenous Group Transferases; D000604:Amino Acyl-tRNA Synthetases; D001226:Aspartate-tRNA Ligase; C100134:prolyl T RNA synthetase; C029194:asparaginyl-tRNA synthetase