2012/06/21 by Petter Hammar, Prune Leroy, Anel Mahmutovic +3 · 3 citations
Biochemistry, Genetics and Molecular Biology · #Diffusion and Search Dynamics #RNA and protein synthesis mechanisms #DNA and Nucleic Acid Chemistry
paper · doi:10.1126/science.1221648
openalex publication_date 2012/06/21 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/23
Transcription factors (TFs) are proteins that regulate the expression of genes by binding sequence-specific sites on the chromosome. It has been proposed that to find these sites fast and accurately, TFs combine one-dimensional (1D) sliding on DNA with 3D diffusion in the cytoplasm. This facilitated diffusion mechanism has been demonstrated in vitro, but it has not been shown experimentally to be exploited in living cells. We have developed a single-molecule assay that allows us to investigate the sliding process in living bacteria. Here we show that the lac repressor slides 45 ± 10 base pairs on chromosomal DNA and that sliding can be obstructed by other DNA-bound proteins near the operator. Furthermore, the repressor frequently (>90%) slides over its natural lacO(1) operator several times before binding. This suggests a trade-off between rapid search on nonspecific sequences and fast binding at the specific sequence.