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J. Bacteriol., 04 1995, 1872-1878, Vol 177, No. 7
MV Saluta and IN Hirshfield
The lysyl-tRNA synthetase (LysRS) system of Escherichia coli K-12 consists
of two genes, lysS, which is constitutive, and lysU, which is inducible. It
is of importance to know how extensively the two-gene LysRS system is
distributed in procaryotes, in particular, among members of the family
Enterobacteriaceae. To this end, the enterics E. coli K-12 and B; E. coli
reference collection (ECOR) isolates EC2, EC49, EC65, and EC68; Shigella
flexneri; Salmonella typhimurium; Klebsiella pneumoniae; Enterobacter
aerogenes; Serratia marcescens; and Proteus vulgaris and the nonenterics
Pseudomonas aeruginosa and Bacillus megaterium were grown in AC broth to a
pH of 5.5 or less or cultured in SABO medium at pH 5.0. These growth
conditions are known to induce LysRS activity (LysU synthesis) in E. coli
K-12. Significant induction of LysRS activity (twofold or better) was
observed in the E. coli strains, the ECOR isolates, S. flexneri, K.
pneumoniae, and E. aerogenes. To demonstrate an association between LysRS
induction and two distinct LysRS genes, Southern blotting was performed
with a probe representing an 871-bp fragment amplified from an internal
portion of the coding region of the lysU gene. In initial experiments,
chromosomal DNA from E. coli K-12 strain MC4100 (lysS+ lysU+) was double
digested with either BamHI and HindIII or BamHI and SalI, producing
hybridizable fragments of 12.4 and 4.2 kb and 6.6 and 5.2 kb, respectively.
Subjecting the chromosomal DNA of E. coli K-12 strain GNB10181 (lysS+ delta
lysU) to the same regimen established that the larger fragment from each
digestion contained the lysU gene.(ABSTRACT TRUNCATED AT 250 WORDS)
Copyright © 1995, American Society for Microbiology
The occurrence of duplicate lysyl-tRNA synthetase gene homologs in Escherichia coli and other procaryotes
Department of Biological Sciences, St. John's University, Jamaica, New York.
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