Role of Lysine-195 in the Kmsks Sequence of Escherichia-Coli Tryptophanyl-Transfer-Rna Synthetase
by Chan, K. W.; Koeppe, R. E.
Lysine 195 in the K-195 MSKS sequence of E. coli tryptophanyl-tRNA synthetase (TrpRS) was replaced with alanine. The resulting K195A mutant TrpRS had essentially unchanged K-m values for ATP and Trp, but a 1500-fold decreased k(cat) in a pyrophosphate-ATP exchange reaction. This large decrease in k(cat) reduces the rate of aminoacyladenylate formation (step 1) to a rate comparable to the rate of aminoacylation of tRNA(Trp) (step 2) by the K195A mutant enzyme. Both the TIGN and KMSKS sequences are important for step 1 of class I aminoacyl-tRNA synthetase reactions.
- Journal
- FEBS Letters
- Volume
- 363
- Issue
- 1-2
- Year
- 1995
- Start Page
- 33-36
- URL
- https://dx.doi.org/10.1016/0014-5793(95)00274-d
- ISBN/ISSN
- 1873-3468; 0014-5793
- DOI
- 10.1016/0014-5793(95)00274-d