Gelsolin-Mediated Actin Filament Severing, Mechanics, and Conformational Changes by Various pH
ORAL
Abstract
Gelsolin is a calcium (Ca2+) dependent, pH sensitive actin-binding protein that regulates actin filament dynamics to remodel the actin cytoskeleton. It is known that gelsolin binding induces conformational changes of actin filaments, leading to filament severing. However, the influence of physiological conditions, such as pH variations, on gelsolin-mediated filament severing activities, mechanics and conformations remains unclear despite their role in actin-actin interactions. Using Total Internal Reflection Fluorescence (TIRF) microscopy imaging and pyrene fluorescence assays, we demonstrate that filament severing efficiencies by gelsolin are enhanced in acidic conditions. In addition, analysis of filament thermal fluctuations using TIRF reveals that gelsolin binding stiffens actin filaments. Furthermore, we show that gelsolin binding induces conformational changes in filaments by measuring the filament half-pitch using high resolution Atomic Force Microscopy imaging. Together, our results suggest that pH modulation plays a key role in gelsolin-mediated filament severing activities, bending mechanics, and conformational changes, which have implications in many cellular processes including cell motility and morphogenesis.
*The research reported in this publication is supported by the National Science Foundation under the CAREER Award 1943266 (to E.H.K). This content is solely the responsibility of the authors and does not represent the National Science Foundation. We acknowledge the University of Central Florida ORCGS Doctoral Fellowship (to T.V.D.).
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Presenters
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Taylor V Douglas
- University of Central Florida