13CT
Crystal structure of Sulfide-responsive transcriptional repressor (SqrR) from Rhodobacter capsulatus bound to DNA
Summary for 13CT
| Entry DOI | 10.2210/pdb13ct/pdb |
| Descriptor | Transcriptional regulator, ArsR family, rcc1451NMR, CHLORIDE ION, ... (4 entities in total) |
| Functional Keywords | transcriptional regulator, sulfide-responsive, dna-complex, arsr protein, bacterial allosteric transcription factor, transcription |
| Biological source | Rhodobacter capsulatus More |
| Total number of polymer chains | 2 |
| Total formula weight | 19316.32 |
| Authors | Antelo, G.T.,Gonzalez-Gutierrez, G.,Giedroc, D.P.,Capdevila, D.A. (deposition date: 2026-04-30, release date: 2026-07-15) |
| Primary citation | Antelo, G.T.,Rondon, J.J.,Villarruel Dujovne, M.,Pis Diez, C.M.,Cancian, P.G.,Sastre, S.,Zeida, A.,Radi, R.,Wu, H.,Gonzalez-Gutierrez, G.,Giedroc, D.P.,Capdevila, D.A. Evolution of allostery without shape shifting: Internal dynamics drives functional diversification of a transcriptional repressor superfamily. Biorxiv, 2026 Cited by PubMed Abstract: Allostery enables proteins to couple environmental signals to functional outputs, yet how allosteric mechanisms diversify during evolution remains poorly understood. Here, we address this question in the ubiquitous and functionally diverse arsenic repressor (ArsR) superfamily by integrating information-theoretic bioinformatics, structural characterization of DNA recognition and NMR measurements of fast internal dynamics. We identify conserved residues that define the structural scaffold of ArsR proteins and subfamily-specific positions that encode inducer and DNA specificity. In the persulfide sensor SqrR, the crystal structure of the DNA-bound complex reveals how operator specificity is encoded by a limited set of residues, consistent with sequence-derived predictions functionally validated by in vitro transcription assays across divergent ArsR regulators. We further show that allosteric inhibition of DNA binding in SqrR occurs without large-scale conformational rearrangements and is instead associated with changes in internal dynamics, as previously observed for the zinc sensor CzrA. Together, these results support a model in which conformational entropy preserves allosteric connectivity while relaxing sequence constraints, thereby enabling functional diversification within a protein superfamily. PubMed: 42182359DOI: 10.64898/2026.05.15.721447 PDB entries with the same primary citation |
| Experimental method | X-RAY DIFFRACTION (1.91 Å) |
Structure validation
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