Share Email Print
cover

Proceedings Paper

Mechanics of protein-DNA interaction studied with ultra-fast optical tweezers
Author(s): Carina Monico; Alessia Tempestini; Francesco Vanzi; Francesco S. Pavone; Marco Capitanio
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

The lac operon is a well known example of gene expression regulation, based on the specific interaction of Lac repressor protein (LacI) with its target DNA sequence (operator). LacI and other DNA-binding proteins bind their specific target sequences with rates higher than allowed by 3D diffusion alone. Generally accepted models predict a combination of free 3D diffusion and 1D sliding along non-specific DNA. We recently developed an ultrafast force-clamp laser trap technique capable of probing molecular interactions with sub-ms temporal resolution, under controlled pN-range forces. With this technique, we tested the interaction of LacI with two different DNA constructs: a construct with two copies of the O1 operator separated by 300 bp and a construct containing the native E.coli operator sequences. Our measurements show at least two classes of LacI-DNA interactions: long (in the tens of s range) and short (tens of ms). Based on position along the DNA sequence, the observed interactions can be interpreted as specific binding to operator sequences (long events) and transient interactions with nonspecific sequences (short events). Moreover, we observe continuous sliding of the protein along DNA, passively driven by the force applied with the optical tweezers.

Paper Details

Date Published: 8 May 2014
PDF: 6 pages
Proc. SPIE 9129, Biophotonics: Photonic Solutions for Better Health Care IV, 91291X (8 May 2014); doi: 10.1117/12.2052545
Show Author Affiliations
Carina Monico, European Lab. for Non-Linear Spectroscopy (Italy)
Alessia Tempestini, European Lab. for Non-Linear Spectroscopy (Italy)
Francesco Vanzi, European Lab. for Non-Linear Spectroscopy (Italy)
Univ. degli Studi di Firenze (Italy)
Francesco S. Pavone, European Lab. for Non-Linear Spectroscopy (Italy)
Univ. degli Studi di Firenze (Italy)
Instituto Nazionale di Ottica, CNR (Italy)
Marco Capitanio, European Lab. for Non-Linear Spectroscopy (Italy)
Univ. degli Studi di Firenze (Italy)


Published in SPIE Proceedings Vol. 9129:
Biophotonics: Photonic Solutions for Better Health Care IV
Jürgen Popp; Valery V. Tuchin; Dennis L. Matthews; Francesco Saverio Pavone; Paul Garside, Editor(s)

© SPIE. Terms of Use
Back to Top