Oligomerization of NTRC at the glnA enhancer is required for transcriptional activation.
To activate transcription of the glnA gene, the dimeric NTRC protein (nitrogen regulatory protein C) of enteric bacteria binds to an enhancer located approximately 100 bp upstream of the promoter. The enhancer is composed of two binding sites for NTRC that are three turns of the DNA helix apart. One role of the enhancer is to tether NTRC in high local concentration near the promoter to allow for its frequent interaction with sigma 54 holoenzyme by DNA looping. We have found that a second role of the enhancer is to ensure oligomerization of NTRC into a complex of at least two dimers that is required for transcriptional activation. Formation of this complex is greatly facilitated by a protein-protein interaction between NTRC dimers that is increased when the protein is phosphorylated.
Porter
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Department of Plant Biology, University of California, Berkeley 94720.
North
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AK
Wedel
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Kustu
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D001426:Bacterial Proteins; D001483:Base Sequence; D017931:DNA Primers; D004269:DNA, Bacterial / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D005798:Genes, Bacterial; D005974:Glutamate-Ammonia Ligase / Q000235:genetics*; D007700:Kinetics; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D051922:PII Nitrogen Regulatory Proteins; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D015534:Trans-Activators; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D051922:PII Nitrogen Regulatory Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D005974:Glutamate-Ammonia Ligase