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dc.contributor.advisorMatthew J. Lang and Roger D. Kamm.en_US
dc.contributor.authorFerrer, Jorge M., 1976-en_US
dc.contributor.otherMassachusetts Institute of Technology. Biological Engineering Division.en_US
dc.date.accessioned2008-03-27T18:27:06Z
dc.date.available2008-03-27T18:27:06Z
dc.date.copyright2007en_US
dc.date.issued2007en_US
dc.identifier.urihttp://hdl.handle.net/1721.1/40950
dc.descriptionThesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2007.en_US
dc.descriptionIncludes bibliographical references.en_US
dc.description.abstractMechanical forces play an important role in cell morphology, orientation, migration, adhesion and can even induce apoptosis. The eukaryotic cell is equipped with a dynamic frame, known as the cytoskeleton, that provides the cell's structural integrity in order to sustain and react to such forces. Therefore, understanding the mechanical properties of the cytoskeleton is an important step towards building models describing cell behavior. Filamentous actin (F-actin), as one of the major constituents of the cytoskeleton, has been the target of extensive in vitro studies to determine its mechanical properties in bulk. However, there is still a lack in the understanding of how the molecular interactions between F-actin and the proteins that arrange these filaments into networks regulate the dynamic properties of the cytoskeleton Here we present a novel, single molecule assay to test the rupture force of a complex formed by an actin binding protein (ABP) linking two actin filaments. We readily demonstrate the adaptability of this assay by testing it with two different ABPs: filamin, a crosslinker, and a-actinin, a bundler. We measured rupture forces of 28-73 pN and 30-56 pN for filamin/actin and a-actinin/actin respectively, suggesting that the former is a slightly stronger interaction. Moreover, since no ABP unfolding events were observed at our force levels, our results suggest that ABP unbinding is a more relevant mechanism than unfolding for the temporal regulation of the mechanical properties of the actin cytoskeleton. In addition, we explore the micro-scale properties of F-actin networks reconstituted in vitro.en_US
dc.description.abstract(cont.) Using imaging and microrheology techniques we characterized the effects of filament length and degree of crosslinking on the structural arrangement and mechanical properties of F-actin networks. We found that the mechanical properties of these networks are length-scale dependent. Also, when probed with active methods, the F-actin networks exhibited strain hardening followed by a gradual softening at forces -30 pN, in good agreement with the single molecule rupture force of 28-73 pN. Thus, with the combination of single molecule and network studies, we can expand the knowledge-base on the regulation and control of the cellular machinery starting from the molecular building blocks.en_US
dc.description.statementofresponsibilityby Jorge M. Ferrer.en_US
dc.format.extent134 p.en_US
dc.language.isoengen_US
dc.publisherMassachusetts Institute of Technologyen_US
dc.rightsMIT theses are protected by copyright. They may be viewed, downloaded, or printed from this source but further reproduction or distribution in any format is prohibited without written permission.en_US
dc.rights.urihttp://dspace.mit.edu/handle/1721.1/7582en_US
dc.subjectBiological Engineering Division.en_US
dc.titleMapping the actin and actin binding proteins interactions : from micromechanics to single molecule force spectroscopyen_US
dc.typeThesisen_US
dc.description.degreePh.D.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Biological Engineering Division.en_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Biological Engineering
dc.identifier.oclc212626718en_US


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