13ct

Crystal structure of Sulfide-responsive transcriptional repressor (SqrR) from Rhodobacter capsulatus bound to DNA

spinqualitylabelsall models 13ct, resolution 1.91Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 13ct is a 2 chain structure with sequence from Rhodobacter capsulatus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.91Å Ligands: CL, CSD, MSE Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function D5AT91_RHOCB Publication Abstract from PubMed 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. Evolution of allostery without shape shifting: Internal dynamics drives functional diversification of a transcriptional repressor superfamily.,Antelo GT, Rondon JJ, Villarruel Dujovne M, Pis Diez CM, Cancian PG, Sastre S, Zeida A, Radi R, Wu H, Gonzalez-Gutierrez G, Giedroc DP, Capdevila DA bioRxiv [Preprint]. 2026 May 16:2026.05.15.721447. doi: , 10.64898/2026.05.15.721447. PMID:42182359 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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