Molecular Mechanisms Underlying the Positive Stringent Response of the Bacillus subtilis ilv-leu Operon, Involved in the Biosynthesis of Branched-Chain Amino Acids
| Autor: | Takenori Satomura, Kazutake Hirooka, Shigeo Tojo, Yasutaro Fujita, Kanako Kumamoto |
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| Rok vydání: | 2008 |
| Předmět: |
Adenosine
Transcription Genetic GTP' Operon Stringent response lac operon Genetics and Molecular Biology Bacillus subtilis Microbiology Ligases chemistry.chemical_compound Bacterial Proteins Biosynthesis Genes Reporter Transcription (biology) Promoter Regions Genetic Molecular Biology Sequence Deletion chemistry.chemical_classification Base Sequence biology Lysine Gene Expression Regulation Bacterial Ribonucleotides biology.organism_classification Amino acid DNA-Binding Proteins Repressor Proteins chemistry Biochemistry Amino Acids Branched-Chain |
| Zdroj: | Journal of Bacteriology. 190:6134-6147 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.00606-08 |
| Popis: | Branched-chain amino acids are the most abundant amino acids in proteins. The Bacillus subtilis ilv-leu operon is involved in the biosynthesis of branched-chain amino acids. This operon exhibits a RelA-dependent positive stringent response to amino acid starvation. We investigated this positive stringent response upon lysine starvation as well as decoyinine treatment. Deletion analysis involving various lacZ fusions revealed two molecular mechanisms underlying the positive stringent response of ilv-leu , i.e., CodY-dependent and -independent mechanisms. The former is most likely triggered by the decrease in the in vivo concentration of GTP upon lysine starvation, GTP being a corepressor of the CodY protein. So, the GTP decrease derepressed ilv-leu expression through detachment of the CodY protein from its cis elements upstream of the ilv-leu promoter. By means of base substitution and in vitro transcription analyses, the latter (CodY-independent) mechanism was found to comprise the modulation of the transcription initiation frequency, which likely depends on fluctuation of the in vivo RNA polymerase substrate concentrations after stringent treatment, and to involve at least the base species of adenine at the 5′ end of the ilv-leu transcript. As discussed, this mechanism is presumably distinct from that for B. subtilis rrn operons, which involves changes in the in vivo concentration of the initiating GTP. |
| Databáze: | OpenAIRE |
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