2rbf

Structure of the ribbon-helix-helix domain of Escherichia coli PutA (PutA52) complexed with operator DNA (O2)

spinqualitylabelsall models 2rbf, resolution 2.25Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2rbf is a 4 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.25Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PUTA_ECOLI Oxidizes proline to glutamate for use as a carbon and nitrogen source and also function as a transcriptional repressor of the put operon. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The multifunctional Escherichia coli proline utilization A (PutA) flavoprotein functions both as a membrane-associated proline catabolic enzyme and as a transcriptional repressor of the proline utilization genes putA and putP. To better understand the mechanism of transcriptional regulation by PutA, we have mapped the put-regulatory region, determined a crystal structure of the PutA ribbon-helix-helix domain (PutA52, a polypeptide corresponding to residues 1-52 of E. coli PutA) complexed with DNA, and examined the thermodynamics of DNA binding to PutA52. Five operator sites, each containing the sequence motif 5'-GTTGCA-3', were identified using gel-shift analysis. Three of the sites are shown to be critical for repression of putA, whereas the two other sites are important for repression of putP. The 2.25-A-resolution crystal structure of PutA52 bound to one of the operators (operator 2; 21 bp) shows that the protein contacts a 9-bp fragment corresponding to the GTTGCA consensus motif plus three flanking base pairs. Since the operator sequences differ in flanking bases, the structure implies that PutA may have different affinities for the five operators. This hypothesis was explored using isothermal titration calorimetry. The binding of PutA52 to operator 2 is exothermic, with an enthalpy of -1.8 kcal/mol and a dissociation constant of 210 nM. Substitution of the flanking bases of operator 4 into operator 2 results in an unfavorable enthalpy of 0.2 kcal/mol and a 15-fold-lower affinity, showing that base pairs outside of the consensus motif impact binding. Structural and thermodynamic data suggest that hydrogen bonds between Lys9 and bases adjacent to the GTTGCA motif contribute to transcriptional regulation by fine-tuning the affinity of PutA for put control operators. Structural basis of the transcriptional regulation of the proline utilization regulon by multifunctional PutA.,Zhou Y, Larson JD, Bottoms CA, Arturo EC, Henzl MT, Jenkins JL, Nix JC, Becker DF, Tanner JJ J Mol Biol. 2008 Aug 1;381(1):174-88. Epub 2008 Jun 7. PMID:18586269 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Proline utilization A

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