Activities | Families | Sequences | Fold types | References | Help
B6db references: 1339259

type Journal Article
authors Hirahara, T.; Suzuki, S.; Horinouchi, S.; Beppu, T.
title Cloning, nucleotide sequences, and overexpression in Escherichia coli of tandem copies of a tryptophanase gene in an obligately symbiotic thermophile, Symbiobacterium thermophilum
journal Appl Environ Microbiol
sel selected
ui 1339259
year (1992)
volume 58
number 8
pages 2633-42
keywords Amino Acid Sequence
abstract Symbiobacterium thermophilum, a thermophilic bacterium, is a thermostable tryptophanase producer that can grow only in coculture with a specific Bacillus strain. Two thermostable tryptophanase genes, tna-1 and tna-2, that are located close to each other were cloned into Escherichia coli from S. thermophilum by the DNA-probing method. The nucleotide and deduced amino acid sequences indicate that Tna1 and Tna2 share 92% identical amino acids in a total of 453 amino acids. By means of DNA manipulation with E. coli host-vector systems, Tna1 and Tna2 were produced in very large amounts in enzymatically active forms. Comparison of the NH2-terminal amino acid sequences and the enzymatic properties of the tryptophanases purified from the original S. thermophilum strain and these two tryptophanases from recombinant E. coli cells suggest that in S. thermophilum, only Tna2 is produced and tna-1 is silent. Notwithstanding the great similarity in amino acid sequence between Tna1 and Tna2, the two enzymes differ markedly in activation energy for catalysis and thermostability.
last changed 2009/06/23 09:37

B6db references