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Co‐ordinate expression of the two threonyl‐tRNA synthetase genes in Bacillus subtilis: control by transcriptional antitermination involving a conserved regulatory sequence.
Author(s) -
Putzer H.,
Gendron N.,
GrunbergManago M.
Publication year - 1992
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1992.tb05384.x
Subject(s) - bacillus subtilis , transfer rna , biology , gene , antitermination , microbiology and biotechnology , genetics , physics , rna , rna polymerase , bacteria
In Bacillus subtilis, two genes, thrS and thrZ, encode distinct threonyl‐tRNA synthetase enzymes. Normally, only the thrS gene is expressed. Here we show that either gene, thrS or thrZ, is sufficient for normal cell growth and sporulation. Reducing the intracellular ThrS protein concentration induces thrZ expression in a dose‐compensatory manner. Starvation for threonine simultaneously induces thrZ and stimulates thrS expression. The 5′‐leader sequences of thrS and thrZ contain, respectively, one and three transcription terminators preceded by a conserved sequence. We show that this sequence is essential for the regulation of thrS via a transcriptional antitermination mechanism. We propose that both genes, thrS and thrZ, are regulated by the same mechanism such that the additional regulatory domains present before thrZ account for its non‐expression. In contrast to Escherichia coli, structurally similar regulatory domains, i.e. the consensus sequence preceding a terminator structure, are found in the leader regions of most aminoacyl‐tRNA synthetase genes of Gram‐positive bacteria. This suggests that they are regulated by a common mechanism.