ALANYL-TRANSFER-RNA SYNTHETASE GENE OF THE EXTREME ACIDOPHILIC CHEMOLITHOAUTOTROPHIC THIOBACILLUS-FERROOXIDANS IS HIGHLY HOMOLOGOUS TO ALASGENES FROM ALL LIVING KINGDOMS BUT CANNOT BE TRANSCRIBED FROM ITS PROMOTER IN ESCHERICHIA-COLI
N. Guiliani et al., ALANYL-TRANSFER-RNA SYNTHETASE GENE OF THE EXTREME ACIDOPHILIC CHEMOLITHOAUTOTROPHIC THIOBACILLUS-FERROOXIDANS IS HIGHLY HOMOLOGOUS TO ALASGENES FROM ALL LIVING KINGDOMS BUT CANNOT BE TRANSCRIBED FROM ITS PROMOTER IN ESCHERICHIA-COLI, Microbiology, 143, 1997, pp. 2179-2187
The alaS gene of Thiobacillus ferrooxidans has been cloned and sequenc
ed and its expression in Escherichia coli and T. ferrooxidans analysed
. The same genomic organization to that in E. coil (recA-recX-alaS) ha
s been found in T. ferrooxidans. The recA and alaS genes cannot be tra
nscribed from their own promoters in E. coli. In addition to the well-
known homology at the protein level between AlaS proteins from various
organisms, a strong homology was found between all the known alaS gen
es from bacteria, archaea and eucarya. Two regions, one of which corre
sponds to the catalytic core, are particularly well-conserved at the n
ucleotide sequence level, a possible indication of strong constraints
during evolution on these parts of the genes.