Fluorescence Spectroscopic Analysis of ppGpp Binding to cAMP Receptor Protein and Histone-Like Nucleoid Structuring Protein
The cyclic AMP receptor protein (CRP) is one of the best-known transcription factors, regulating about 400 genes. The histone-like nucleoid structuring protein (H-NS) is one of the nucleoid-forming proteins and is responsible for DNA packaging and gene repression in prokaryotes. In this study, the b...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-07-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/22/15/7871 |
| Summary: | The cyclic AMP receptor protein (CRP) is one of the best-known transcription factors, regulating about 400 genes. The histone-like nucleoid structuring protein (H-NS) is one of the nucleoid-forming proteins and is responsible for DNA packaging and gene repression in prokaryotes. In this study, the binding of ppGpp to CRP and H-NS was determined by fluorescence spectroscopy. CRP from <i>Escherichia coli</i> exhibited intrinsic fluorescence at 341 nm when excited at 280 nm. The fluorescence intensity decreased in the presence of ppGpp. The dissociation constant of 35 ± 3 µM suggests that ppGpp binds to CRP with a similar affinity to cAMP. H-NS also shows intrinsic fluorescence at 329 nm. The fluorescence intensity was decreased by various ligands and the calculated dissociation constant for ppGpp was 80 ± 11 µM, which suggests that the binding site was occupied fully by ppGpp under starvation conditions. This study suggests the modulatory effects of ppGpp in gene expression regulated by CRP and H-NS. The method described here may be applicable to many other proteins. |
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| ISSN: | 1661-6596 1422-0067 |