Sliding of a single lac repressor protein along DNA is tuned by DNA sequence and molecular switching.

ABSTRACT: In any living cell, genome maintenance is carried out by DNA-binding proteins that recognize specific sequences among a vast amount of DNA. This includes fundamental processes such as DNA replication, DNA repair, and gene expression and regulation. Here, we study the mechanism of DNA target search by a single lac repressor protein (LacI) with ultrafast force-clamp spectroscopy, a sub-millisecond and few base-pair resolution technique based on laser tweezers. We measure 1D-diffusion of proteins on DNA at physiological salt concentrations with 20 bp resolution and find that sliding of LacI along DNA is sequence dependent. We show that only allosterically activated LacI slides along non-specific DNA sequences during target search, whereas the inhibited conformation does not support sliding an

SUBMITTER: Tempestini A 

PROVIDER: S-EPMC6007606 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature