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In vivo non‐specific binding of λ CI and Cro repressors is significant
Author(s) -
Bakk Audun,
Metzler Ralf
Publication year - 2004
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(04)00249-2
Subject(s) - in vivo , repressor , binding energy , chemistry , lysogen , monomer , biochemistry , crystallography , biophysics , biology , bacteriophage , physics , genetics , gene , gene expression , organic chemistry , escherichia coli , polymer , nuclear physics
We propose a thermodynamic model that includes the non‐specific binding of the λ phage regulatory proteins CI and Cro. By fitting the model to experimental in vivo data on activities of the two promoters P RM and P R versus concentration, we estimate the free energy upon non‐specific binding to be −4.1±0.9 kcal/mol for CI and −4.2±0.8 kcal/mol for Cro. For concentrations >100 nM of CI or Cro, we find that >50% of these proteins are non‐specifically bound. In particular, in a lysogen (∼250 CI monomeric equivalents per cell) nearly 90% of CI is non‐specifically bound.