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Dimerization of the operator binding domain of phage lambda repressor

Journal Article · · Biochemistry; (United States)
DOI:https://doi.org/10.1021/bi00377a034· OSTI ID:6524717
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Dimerization of lambda repressor is required for its binding to operator DNA. As part of a continuing study of the structural basis of the coupling between dimer formation and operator binding, the authors have undertaken /sup 1/H NMR and gel filtration studies of the dimerization of the N-terminal domain of lambda repressor. Five protein fragments have been studied: three are wild-type fragments of different length (1-102, 1-92, and 1-90), and two are fragments bearing single amino acid substitutions in residues involved in the dimer interface (1-102, Tyr-88 ..-->.. Cys; 1-92, Ile-84 ..-->.. Ser). The tertiary structure of each species is essentially the same, as monitored by the /sup 1/H NMR resonances of internal aromatic groups. However, significant differences are observed in their dimerization properties. /sup 1/H NMR resonances of aromatic residues that are involved in the dimer contact allow the monomer-dimer equilibrium to be monitored in solution. The structure of the wild-type dimer contact appears to be similar to that deduced from X-ray crystallography and involves the hydrophobic packing of symmetry-related helices (helix 5) from each monomer. Removal of two contact residues, Val-91 and Ser-92, by limited proteolysis disrupts this interaction and also prevents crystallization. The Ile-84 ..-->.. Ser substitution also disrupts this interaction, which accounts for the severely reduced operator affinity of this mutant protein.
Research Organization:
Harvard Univ., Cambridge, MA
OSTI ID:
6524717
Journal Information:
Biochemistry; (United States), Journal Name: Biochemistry; (United States) Vol. 26:3; ISSN BICHA
Country of Publication:
United States
Language:
English

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Related Subjects

550601* -- Medicine-- Unsealed Radionuclides in Diagnostics
550602 -- Medicine-- External Radiation in Diagnostics-- (1980-)
62 RADIOLOGY AND NUCLEAR MEDICINE
AMINO ACIDS
BACTERIA
BACTERIOPHAGES
BARYONS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CHROMATOGRAPHY
COHERENT SCATTERING
DIFFRACTION
DIMERIZATION
ELEMENTARY PARTICLES
ESCHERICHIA COLI
FERMIONS
FILTRATION
GENOTYPE
HADRONS
HYDROXY ACIDS
LEUCINE
LIQUID COLUMN CHROMATOGRAPHY
MAGNETIC RESONANCE
MICROORGANISMS
NUCLEAR MAGNETIC RESONANCE
NUCLEONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
PARASITES
POLYMERIZATION
PROTEINS
PROTONS
RESONANCE
SCATTERING
SEPARATION PROCESSES
SERINE
VALINE
VIRUSES
X-RAY DIFFRACTION