Force-driven unbinding of proteins HU and Fis from DNA quantified using a thermodynamic Maxwell relation.

ABSTRACT: Determining numbers of proteins bound to large DNAs is important for understanding their chromosomal functions. Protein numbers may be affected by physical factors such as mechanical forces generated in DNA, e.g. by transcription or replication. We performed single-DNA stretching experiments with bacterial nucleoid proteins HU and Fis, verifying that the force-extension measurements were in thermodynamic equilibrium. We, therefore, could use a thermodynamic Maxwell relation to deduce the change of protein number on a single DNA due to varied force. For the binding of both HU and Fis under conditions studied, numbers of bound proteins decreased as force was increased. Our experiments showed that most of the bound HU proteins were driven off the DNA at 6.3 pN for HU concentrations lower than

SUBMITTER: Xiao B 

PROVIDER: S-EPMC3141252 | biostudies-literature | 2011 Jul

REPOSITORIES: biostudies-literature