Nucleic Acids Research, Vol 25, Issue 14 2737-2744, Copyright © 1997 by Oxford University Press
A Lechler, A Martin, T Zuleeg, S Limmer and R Kreutzer
The alaS gene encoding the alanyl-tRNA synthetase (AlaRS) from Thermus
thermophilus HB8 was cloned and sequenced. The gene comprises 2646 bp,
corresponding to 882 amino acids, 45% of which are identical to the enzyme
from Escherichia coli . The T. thermophilus AlaRS was overproduced in
E.coli , purified and characterized. It has high thermal stability up to
approximately 65 degrees C, with a temperature optimum of aminoacylation
activity at approximately 60 degrees C, and will be valuable for
crystallization. The purified enzyme appears as a dimer with a specific
activity of 220 U/mg and k cat/ K M values of 118 000/s/M for alanine and
114 000/s/M for ATP. By genetic engineering a 53 kDa fragment of AlaRS
comprising the N-terminal 470 amino acids (AlaN470) was also overproduced
and purified. It is as stable as entire AlaRS and sufficient for specific
aminoacylation of intact tRNAAla, as well as acceptor stem microhelices
with a G3-U70, but not U3-A70, I3- U70 or C3-U70, base pair. The reduced
binding strength of such microhelices to AlaN470 enabled, due to the
resulting fast exchange of the microhelices between free and complexed
states, preliminary NMR analyses of the binding mode and intermolecular
recognition.
ARTICLES
A biologically active 53 kDa fragment of overproduced alanyl-tRNA synthetase from Thermus thermophilus HB8 specifically interacts with tRNA Ala acceptor helix
Laboratorium fur Biochemie, Universitat Bayreuth, Universitatsstrasse 30, 95447 Bayreuth, Germany.
![]()
CiteULike
Connotea
Del.icio.us What's this?
This article has been cited by other articles:
![]() |
M. Sissler, C. Delorme, J. Bond, S. D. Ehrlich, P. Renault, and C. Francklyn An aminoacyl-tRNA synthetase paralog with a catalytic role in histidine biosynthesis PNAS, August 3, 1999; 96(16): 8985 - 8990. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Ribas de Pouplana and P. Schimmel Operational RNA Code for Amino Acids in Relation to Genetic Code in Evolution J. Biol. Chem., March 2, 2001; 276(10): 6881 - 6884. [Full Text] [PDF] |
||||

