NANOSCALE THERMODYNAMICS OF MECHANOSENSITIVE ION CHANNELS AND THEIR ROLE IN THE MECHANISM OF OSMOTIC FITNESS OF MICROBES

Simple item page
dc.contributor.advisorSukharev, Sergeien_US
dc.contributor.authorCetiner, Uguren_US
dc.contributor.departmentBiophysics (BIPH)en_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2018-09-12T05:54:20Z
dc.date.available2018-09-12T05:54:20Z
dc.date.issued2018en_US
dc.description.abstractBacterial mechanosensitive channels are major players in cells’ ability to cope with hypo-osmotic stress. Excess turgor pressure due to fast water influx is reduced as the channels, triggered by membrane tension, open and release osmolytes. In bacteria, the bulk release of ions and other osmolytes is mainly mediated by two families of mechanosensitive channels: MscS and MscL. The MscL family channels form large non-selective pathways in the membrane and gate near the lytic tension. In this way, they act as a final back up mechanism against osmotic downshock. MscS family channels require less tension to open and display great diversity in structure and functionality. Chapter 2 describes the first multifaceted phenomenological study of the emergency osmolyte release system in wild type Pseudomonas aeruginosa in comparison with E.coli. We recorded the kinetics of cell equilibration reported by light scattering responses to osmotic up- and down-shocks using the stopped-flow technique. We also performed the first electrophysiological characterization of the mechanosensitive ion channels in Pseudomonas aeruginosa. We presented a quantitative biophysical description of “osmotic fitness” which would be of interest to microbiologists, epidemiologists, ecologists and general environmental scientists. Chapter 3 presents the combined theoretical and experimental analysis of the full functional cycle of the bacterial channel MscS, which plays a major role in osmotic adjustments and environmental stability of most bacteria. We modeled MscS gating as a finite state continuous-time Markov chain and obtained analytical expressions for the steady state solution and the inactivated state area (which is experimentally hard to determine). In Chapter 4, we derived a general formalism to extract the free energy difference between the closed and open states of mechanosensitive ion channels (ΔF) from non-equilibrium work distributions associated with the channels’ gating. Our new approach bridges the gap between recent developments in non-equilibrium thermodynamics of small systems and ion channel biophysics. Our study also serves as an experimental verification of non-equilibrium work relations in a biological system. Therefore, the results in this thesis are sufficiently general and would be of interest to a broad community.en_US
dc.identifierhttps://doi.org/10.13016/M2H41JQ9F
dc.identifier.urihttp://hdl.handle.net/1903/21273
dc.language.isoenen_US
dc.subject.pqcontrolledBiophysicsen_US
dc.subject.pqcontrolledThermodynamicsen_US
dc.subject.pqcontrolledApplied physicsen_US
dc.subject.pquncontrolledIon channel biophysicsen_US
dc.subject.pquncontrolledMarkov chainsen_US
dc.subject.pquncontrolledMscSen_US
dc.subject.pquncontrolledNon-equilibrium thermodynamicsen_US
dc.subject.pquncontrolledOsmotic fitnessen_US
dc.titleNANOSCALE THERMODYNAMICS OF MECHANOSENSITIVE ION CHANNELS AND THEIR ROLE IN THE MECHANISM OF OSMOTIC FITNESS OF MICROBESen_US
dc.typeDissertationen_US

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
Cetiner_umd_0117E_19222.pdf
Size:
5.14 MB
Format:
Adobe Portable Document Format
Download

Collections

UMD Theses and Dissertations
Physics Theses and Dissertations