Inhibition of glutamine synthetase II expression by the product of the gstI gene.
We report the identification of a previously unrecognized gene that is involved in the regulation of the Rhizobium leguminosarum glnII (glutamine synthetase II) gene. This gene, which is situated immediately upstream of glnII, was identified by means of a deletion/complementation analysis performed in the heterologous background of Klebsiella pneumoniae. It has been designated gstI (glutamine synthetase translational Inhibitor) because, when a complete version of gstI is present, it is possible to detect glnII-specific mRNA, but neither GSII activity nor GSII protein. The gstI gene encodes a small (63 amino acids) protein, which acts in cis or in trans with respect to glnII and is transcribed divergently with respect to glnII from a promoter that was found to be strongly repressed by the nitrogen transcriptional regulator NtrC. A mutated version of GstI lacking the last 14 amino acids completely lost its capacity to repress glnII expression. Our results indicate that gstI mediates the translation inhibition of glnII mRNA and, based on in silico analyses, a mechanism for GstI action is proposed.
International Institute of Genetics and Biophysics, CNR, Via G. Marconi 10, 80125 Naples, Italy.
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Spinosa
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Riccio
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Mandrich
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Manco
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Lamberti
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Iaccarino
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Merrick
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Patriarca
D000595:Amino Acid Sequence; D001426:Bacterial Proteins; D001483:Base Sequence; D015152:Blotting, Northern; D004268:DNA-Binding Proteins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism*; D015151:Immunoblotting; D007711:Klebsiella pneumoniae / Q000235:genetics; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D051922:PII Nitrogen Regulatory Proteins; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D016961:Rhizobium leguminosarum / Q000235:genetics* / Q000378:metabolism; D015534:Trans-Activators / Q000378:metabolism; D014157:Transcription Factors
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C414318:GstI protein, Rhizobium leguminosarum; D051922:PII Nitrogen Regulatory Proteins; D012333:RNA, Messenger; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C083818:glutamine synthetase 2; D005974:Glutamate-Ammonia Ligase