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Volume 10, Issue 8 (Suppl) J Proteomics Bioinform, an open access journal
ISSN: 0974-276X Structural Biology 2017
September 18- 20, 2017
Page 36
Notes:
conferenceseries.com
9th International Conference on
Structural Biology
September 18-20, 2017 Zurich, Switzerland
Marco Capitanio, J Proteomics Bioinform 2017, 10:8(Suppl)
DOI: 10.4172/0974-276X-C1-0100
High-speed optical tweezers for the study of protein-DNA interaction
We developed a constant-force laser trap that allows us to investigate molecular interactions and sub-nanometer
conformational changes occurring on a time scale of few tens of microseconds. The method is effective in studying
the sequence-dependent affinity of DNA-binding proteins along a single DNA molecule. The improvement in time resolution
provides important means of investigation on the long-puzzled mechanism of target search on DNA. In fact, one poorly
understood issue in the field of protein-DNA interaction is how proteins weakly interact with non-cognate DNA sequences
and how they efficiently find the sequence of interest among an extremely large amount of non-specific sequences. Using our
technique, we could discriminate sequence and conformational dependent interactions of a single Lac repressor protein (LacI)
on DNA at physiological salt concentrations. The lac operon is a well-known example of gene expression regulation, based
on the specific interaction of LacI with its cognate DNA sequence (operator). We observed LacI switching between different
interaction modalities on DNA (weak, strong, sliding), depending on the molecule conformation and DNA sequence. We
provide a method for measuring 1D-diffusion constants of DNA-binding proteins along DNA with a spatial resolution of about
30 base pairs, observing a broad distribution of 1D-diffusion constants of LacI and sequence-dependent diffusion constants.
Our measurements provide a model of target-search and molecular switching mechanism of Lac repressor.
Biography
Marco Capitanio is Senior Researcher at the Department of Physics of the University of Florence, Italy, and Group Leader at the European Laboratory for Non-linear
Spectroscopy (LENS). He then obtained his PhD in Physiology. He then joined LENS, a research institute which is part of a European network of laser and spectroscopy
facilities. His research interests lie across Physics and Biology. On one hand, his research is focused on the physics of biological systems and on the development of
techniques for the study of biology at the molecular scale, with a particular interest on optical methods. On the other hand, he is particularly interested in the molecular
mechanisms underlying mechanical regulation of biological systems and the conversion of mechanical signals into changes in gene expression and cell fate.
Marco Capitanio
University of Florence, Italy