Abstract:
:The kinetics of coupling of protein dimerization and DNA binding have been investigated in the biotin repressor system. Two repressor monomers bind to the 40 base-pair biotin operator sequence. In previous analyses of equilibrium-binding data the weak dimerization of the repressor has justified using a model in which two protein monomers bind cooperatively to the operator site. Here, rapid kinetic methods have been used to directly determine the binding mechanism. Results of rapid-mixing DNaseI footprinting measurements of association of the repressor with operator indicate that the binding process involves at least two steps. Results of measurements of the unimolecular dissociation of the complex reveal a half-life of approximately 400 seconds. Analysis of the data using a combination of simulation and global non-linear least-squares analysis provides support for a binding model in which a preformed repressor dimer associates with the biotin operator. This kinetic model is consistent with the previously proposed model for regulation of the functional switch in the repressor from enzyme to site-specific DNA-binding protein.
journal_name
J Mol Bioljournal_title
Journal of molecular biologyauthors
Streaker ED,Beckett Ddoi
10.1016/s0022-2836(02)01308-6keywords:
subject
Has Abstractpub_date
2003-01-31 00:00:00pages
937-48issue
5eissn
0022-2836issn
1089-8638pii
S0022283602013086journal_volume
325pub_type
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