1E52

Solution structure of Escherichia coli UvrB C-terminal domain

Summary for 1E52

• Entry DOI: 10.2210/pdb1e52/pdb
• Related: 1QOJ
• NMR Information: BMRB: 4622
• Descriptor: EXCINUCLEASE ABC SUBUNIT (1 entity in total)
• Functional Keywords: dna excision repair, uvrb, dna repair, uvrc binding domain
• Biological source: ESCHERICHIA COLI
• Total number of polymer chains: 2
• Total formula weight: 14902.92

Authors

Alexandrovich, A.A.,Kelly, G.G.,Frenkiel, T.A.,Moolenaar, G.F.,Goosen, N.N.,Sanderson, M.R.,Lane, A.N. (deposition date: 2000-07-14, release date: 2001-07-12, Last modification date: 2024-06-19)

Primary citation

Alexandrovich, A.A.,Czisch, M.M.,Frenkiel, T.T.,Kelly, G.G.,Goosen, N.N.,Moolenaar, G.G.,Chowdhry, B.B.,Sanderson, M.M.,Lane, A.A.
Solution Structure, Hydrodynamics and Thermodynamics of the Uvrb C-Terminal Domain.
J.Biomol.Struct.Dyn., 19:219-236, 2001

PubMed Abstract: The solution structure, thermodynamic stability and hydrodynamic properties of the 55-residue C-terminal domain of UvrB that interacts with UvrC during excision repair in E. coli have been determined using a combination of high resolution NMR, ultracentrifugation, 15N NMR relaxation, gel permeation, NMR diffusion, circular dichroism and differential scanning calorimetry. The subunit molecular weight is 7,438 kDa., compared with 14.5+/-1.0 kDa. determined by equilibrium sedimentation, indicating a dimeric structure. The structure determined from NMR showed a stable dimer of anti-parallel helical hairpins that associate in an unusual manner, with a small and hydrophobic interface. The Stokes radius of the protein decreases from a high plateau value (ca. 22 A) at protein concentrations greater than 4 microM to about 18 A at concentrations less than 0.1 microM. The concentration and temperature-dependence of the far UV circular dichroism show that the protein is thermally stable (Tm ca. 71.5 degrees C at 36 microM). The simplest model consistent with these data was a dimer dissociating into folded monomers that then unfolds co-operatively. The van't Hoff enthalpy and dissociation constant for both transition was derived by fitting, with deltaH1=23 kJ mol(-1). K1(298)=0.4 microM and deltaH2= 184 kJ mol(-1). This is in good agreement with direct calorimetric analysis of the thermal unfolding of the protein, which gave a calorimetric enthalpy change of 181 kJ mol(-1) and a van't Hoff enthalpy change of 354 kJ mol(-1), confirming the dimer to monomer unfolding. The thermodynamic data can be reconciled with the observed mode of dimerisation. 15N NMR relaxation measurements at 14.1 T and 11.75 T confirmed that the protein behaves as an asymmetric dimer at mM concentrations, with a flexible N-terminal linker for attachment to the remainder of the UvrB protein. The role of dimerisation of this domain in the excision repair mechanism is discussed.

PubMed: 11697728
DOI: 10.1080/07391102.2001.10506734

Experimental method

SOLUTION NMR