Molecular Biophysics of DNA repair nanomachines
Centro Nacional de Biotecnologia (CSIC)
C/Darwin 3, Campus de Cantoblanco 28049 Madrid, Spain
One of the main advantages of the AFM is the ability for imaging in buffers soft materials like biological samples. Despite this, imaging biomolecules in buffer is not simple and care must be taken in sample preparation and imaging conditions. One must adsorb molecules in such a way that the interaction with the supporting surface is weak enough to allow biomolecular interactions but also strong enough to be able to image them. We studied in detail different techniques for AFM imaging in buffer like Tapping, Jumping and Contact modes and evaluate the different sources of damage on soft biological materials
UAM: Pedro J. de Pablo, Jaime Colchero, Julio Gomez, Arturo M. Baro;
NANOTEC: Rafael Fernandez
F. Moreno-Herrero et al. Physical Review E 69, 031915 (2004).
Jumping Mode Scanning Force Microscopy: a tool for precise force control and high-resolution imaging in liquids
F. Moreno-Herrero et al. Ultramicroscopy 96, 167-174 (2003).
DNA height in Scanning Force Microscopy
F. Moreno-Herrero et al. Applied Surface Science 210, 22-26, (2003).
Jumping Mode Scanning Force Microscopy: a suitable technique for imaging DNA in liquids
F. Moreno-Herrero et al. Applied Physics Letters 81, 2620 (2002).
Scanning Force Microscopy Jumping and Tapping modes in liquids
F. Moreno-Herrero et al. Surface Science 453, 152-158 (2000).
The role of shear forces in scanning force microscopy: a comparison between jumping mode and tapping mode
Molecular devices are the final horizon in the miniaturization of electronic technology. The electrical transport properties of molecules are expected to differ dramatically from those of macroscopic conductors, and finding ways to measure these properties at such a small scale is an important challenge of the emerging nanoscience. In particular, DNA is a well-known molecule that appears as a promising molecular-wire candidate. We studied two direct procedures to measure electrical currents through DNA molecules adsorbed on mica and found a lower limit for the resistivity is 10^6 Ohm x cm in agreement with first principle calculations.
UAM: Pedro J. de Pablo, Cristina Gómez, Jaime Colchero, Adriana Gil,
Mar Alvarez, Julio Gómez, José M. Soler, Arturo M. Baró
ICMB: Pablo Ordejón
UNIOVI: Pilar Herrero
NANOTEC: Rafael Fernández, Ignacio Horcas
F. Moreno-Herrero et al. Nanotechnology 14 (2), 128-133, (2003).
Topographic characterization and electrostatic response of M-DNA studied by Atomic Force Microscopy
C.Gómez-Navarro*, F. Moreno-Herrero* et al. Proceedings of the National Academy of Sciences USA 99 (13), 8484-8487 (2002).
Contactless experiments on individual DNA molecules show no evidence for molecular wire behavior
*Shared first authorship
C.Gómez-Navarro et al. Nanotechnology 13, 1-4 (2002).
Scanning force microscopy three-dimensional modes applied to the study of the dielectric response of adsorbed DNA molecules
P.J.de Pablo et al. Physical Review. Letters 85 (23), 4992-4995 (2000).
Absence of dc-conductivity in lambda DNA
Paired helical filaments (PHF) is an aberrant structure present in the brain of Alzheimers disease patients which has been correlated with their degree of dementia. Several groups have indicated that the microtubule associated protein tau is the major component of PHF. Knowledge of the three-dimensional structure of the proteins implicated in neurodegenerative disorders is essential for understanding why and how endogenous proteins may adopt a nonnative folding. We studied the structure of the PHFs using AFM in air and buffer. Then, we compared our experimental results with structural models. From this we conclude that the PHF structure is compatible with two coupled ribbons with an overall height of 20 nm and a width of 10 nm.
UAM: Jaime Colchero, Julio Gómez, Arturo M. Baró
CBM-UAM: José J. Lucas, Miguel Díaz, Felix Hernández, Esteban Montejo, Mar Pérez, Jesús Avila
Fac. Med. -UAM: Pilar Gómez, María A. Morán,
Hospital Prynceps d´Espanya: Isidro Ferrer
CNB-UAM: José M. Valpuesta
M. Diaz-Hernandez et al. Journal of Neoroscience 24(42), 9361-9371 (2004).
The stable component of Huntington's disease inclusions consist of amyloid-like huntingtin filaments that can be purified and that are susceptible to revert in vivo
F. Moreno-Herrero et al. European Polymer Journal 40(5), 927-932 (2004).
Jumping mode atomic force microscopy obtains reproducible images of Alzheimer paired helical filaments in liquids
F. Moreno-Herrero et al. Biophysical Journal 86, 517-525 (2004).
Characterization by atomic force microscopy of Alzheimer paired helical filaments under physiological conditions
F. Moreno-Herrero et al. Journal of Alzheimer's Disease 3, 443-451 (2001).
Characterization by atomic force microscopy of tau polymers assembled in Alzheimer´s disease
Regulation of gene expression is fundamental in biological systems. A systematic search for protein binding sites in gene promoters has been done in recent years. Biochemical techniques are easy and reliable when analysing protein interactions with short pieces of DNA, but are difficult and tedious when long pieces of DNA have to be analysed. We studied the possibilities of AFM for identification of regulatory sequences. We used different transcription factors involved in the phosphate metabolism and glucose repression signalling of the yeast Saccharomyces cerevisiae.
UAM: Jaime Colchero, Arturo M. Baró
UNIOVI: Tamara de la Cera, Romina S. Chaves, Pilar Herrero, Fernando Moreno
T.de la Cera et al. Journal of Molecular Biology 319, 703-714 (2002).
Mediator factor Med8p interacts with the hexokinase 2: Implication in the glucose signalling pathway of Saccharomyces cerevisiae
F. Moreno-Herrero et al. Biochemical and Biophysical Research Communications 280, 151-157 (2001).
Imaging and mapping protein-binding sites on DNA regulatory regions with atomic force microscopy
F. Moreno-Herrero et al. FEBS Letters 459, 427-432 (1999).
Analisis by atomic force microscopy of Med8 binding to cis-acting regulatory elements of the SUC2 and HXK2 genes of Saccharomyces cerevisiae