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You searched for subject:(Kinesin 14). Showing records 1 – 3 of 3 total matches.

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University of California – San Francisco

1. Jonsson, Erik. Mechanisms of Kinesin Processivity.

Degree: Biophysics, 2015, University of California – San Francisco

Kinesins are molecular motors that convert chemical energy, stored in the bonds of ATP, into productive work. They form one of the three branches of cytoskeletal motors – the others being myosins and dyneins. An important subset of molecular motors, in general, are transport motors. By utilizing microtubule filaments as their track, these protein machines shuttle cargo to different destinations within a cell. Processivity, the ability to take multiple ATP-dependent steps along the filament, is an essential characteristic of these transport motors. In this dissertation I explore two distinct mechanisms of kinesin processivity. Previously, the only known mode of processive retrograde microtubule-based transport is achieved via cytoplasmic dynein. Land plants are thought to have lost the gene encoding for cytoplasmic dynein and thus, as of 2012, it was an open question as to whether they relied at all on microtubule based transport. In the first part of this dissertation, I discuss a novel mechanism of processive retrograde microtubule-based transport in Physcomitrella patens (moss). A kinesin-14 motor protein was found to be capable of processively transporting cargo when the motors are clustered together in small cohorts. In the second part, I explore the processivity of kinesin-1, one of the most well-studied molecular motors. Its processivity is known to be due to an allosteric mechanism, referred to as gating, but the nature of the mechanism has remained elusive. The precise gating mechanism of kinesin-1 has been heavily debated in the thirty years since its discovery. By combining modern protein purification techniques with a classical pre-steady state kinetics approach, I demonstrate that the prominent front head gating model, in its current form, is incorrect and needs to be revised.

Subjects/Keywords: Biophysics; Gating; Kinesin; Kinesin-1; Kinesin-14; Processivity

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Jonsson, E. (2015). Mechanisms of Kinesin Processivity. (Thesis). University of California – San Francisco. Retrieved from http://www.escholarship.org/uc/item/17c615bv

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Jonsson, Erik. “Mechanisms of Kinesin Processivity.” 2015. Thesis, University of California – San Francisco. Accessed November 27, 2020. http://www.escholarship.org/uc/item/17c615bv.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Jonsson, Erik. “Mechanisms of Kinesin Processivity.” 2015. Web. 27 Nov 2020.

Vancouver:

Jonsson E. Mechanisms of Kinesin Processivity. [Internet] [Thesis]. University of California – San Francisco; 2015. [cited 2020 Nov 27]. Available from: http://www.escholarship.org/uc/item/17c615bv.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Jonsson E. Mechanisms of Kinesin Processivity. [Thesis]. University of California – San Francisco; 2015. Available from: http://www.escholarship.org/uc/item/17c615bv

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation


Texas A&M University

2. Lakkaraju, Sirish. Computational Studies on the Mechanical Inhomogeneity of Tropomyosin, and the Directed and Cooperative Motility of the Ncd Motor.

Degree: PhD, Biomedical Engineering, 2012, Texas A&M University

Alpha-helical coiled-coils are common protein structural motifs with varied mechanical roles, such as, tropomyosin in muscle contraction or neck-stalks of kinesins and myosins, in motor proteins. Using computer simulations, we characterized elastic properties of coiled-coils both, globally and locally. Normal mode analysis for global elastic properties revealed a buckling instability due to inherently present weak non-bonded forces. We characterized this using a critical buckling length (lc). For coiled-coils, lc was significantly less than their persistence length thereby governing the filament conformation. We also found that mutations to the hydrophobic residues at the knob-into-hole interface affect elasticity of coiled-coils significantly. We built a flexibility map of tropomyosin using a local fluctuation analysis and found regional variations in flexibilities due to such breaks in the knob-into-hole packing. Overall, flexibility varies by more than twofold and increases towards the C-terminal region of the molecule. Actin binding sites in zones and broken core regions due to acidic residues at the hydrophobic face such as, the Asp137 and the Glu218, are found to be the most labile with moduli for splay and broad face bending as 70 nm and 116 nm, respectively. Such variations in flexibility could be relevant to the tropomyosin function, especially for moving across the non-uniform surface of F-actin to regulate myosin binding. Non-claret disjunction (Ncd), is a Kinesin-14 family protein that walks to the microtubule's minus end. Although available structures show its alpha-helical coiled-coil neck in either pre- or post-stroke orientations, little is known about the transition between these two states. Using a combination of molecular dynamics simulations and structural analyses, we find that the neck travel is a guided diffusion involving sequential intermediate contacts with the motor head. The post-stroke is at a higher free-energy minimum than the pre-stroke. The importance of intermediate contacts correlates with the existing motility data including those of mutant Ncds and other members of the kinesin-14 family. While the forward motion has a ~4.5 kBT (kB: Boltzmann constant, T = 300 K) free energy barrier, recovery stroke goes nearly downhill in free energy. The hysteresis in forward and reverse neck motion energetics arises from the mechanical compliance of the protein, and together with guided diffusion, it may be key for the directed motility of Ncd. Although it is known that neighboring Ncds on a microtubule (MT) have an attractive interaction and a group of Ncds act cooperatively, the physical basis of neither this attraction nor the cooperativity is known. From structural analysis of Ncd neighbors on an MT lattice we find that steric hindrances between the coiled-coil neck-stalks of longitudinal neighbors drive synchrony among a group of Ncds on a single protofilament. Across lateral dimers, surface loop L2 of the motor-head (MH) that is not bound to the MT (unbound-MH) in a pre-stroke dimer, is… Advisors/Committee Members: Hwang, Wonmuk (advisor), Kaunas, Roland R. (committee member), Applegate, Brian E. (committee member), Muthuchamy, Mariappan (committee member).

Subjects/Keywords: Tropomyosin; Kinesin-14; Ncd; Motors; coiled-coils; critical buckling length; targeted molecular dynamics; cooperativity

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Lakkaraju, S. (2012). Computational Studies on the Mechanical Inhomogeneity of Tropomyosin, and the Directed and Cooperative Motility of the Ncd Motor. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10316

Chicago Manual of Style (16th Edition):

Lakkaraju, Sirish. “Computational Studies on the Mechanical Inhomogeneity of Tropomyosin, and the Directed and Cooperative Motility of the Ncd Motor.” 2012. Doctoral Dissertation, Texas A&M University. Accessed November 27, 2020. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10316.

MLA Handbook (7th Edition):

Lakkaraju, Sirish. “Computational Studies on the Mechanical Inhomogeneity of Tropomyosin, and the Directed and Cooperative Motility of the Ncd Motor.” 2012. Web. 27 Nov 2020.

Vancouver:

Lakkaraju S. Computational Studies on the Mechanical Inhomogeneity of Tropomyosin, and the Directed and Cooperative Motility of the Ncd Motor. [Internet] [Doctoral dissertation]. Texas A&M University; 2012. [cited 2020 Nov 27]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10316.

Council of Science Editors:

Lakkaraju S. Computational Studies on the Mechanical Inhomogeneity of Tropomyosin, and the Directed and Cooperative Motility of the Ncd Motor. [Doctoral Dissertation]. Texas A&M University; 2012. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10316


Queens University

3. Delorme, Caroline. Structural and Functional Characterization of a Novel Heterodimeric Kinesin in Candida albicans .

Degree: Biochemistry, 2012, Queens University

Kinesins are molecular motors that transport intracellular cargos along microtubules (MTs) and influence the organization and dynamics of the MT cytoskeleton. Their force-generating functions arise from conformational changes in their motor domain as ATP is bound and hydrolyzed, and products are released. In the budding yeast Saccharomyces cerevisiae, the Kar3 kinesin forms heterodimers with one of two non-catalytic kinesin-like proteins, Cik1 and Vik1, which lack the ability to bind ATP, and yet they retain the capacity to bind MTs. Cik1 and Vik1 also influence and respond to the MT-binding and nucleotide states of Kar3, and differentially regulate the functions of Kar3 during yeast mating and mitosis. The mechanism by which Kar3/Cik1 and Kar3/Vik1 dimers operate remains unknown, but has important implications for understanding mechanical coordination between subunits of motor complexes that traverse cytoskeletal tracks. In this study, we show that the opportunistic human fungal pathogen Candida albicans (Ca) harbors a single version of this unique form of heterodimeric kinesin and we present the first in vitro characterization of this motor. Like its budding yeast counterpart, the Vik1-like subunit binds directly to MTs and strengthens the MT-binding affinity of the heterodimer. However, in contrast to ScKar3/Cik1 and ScKar3/Vik1, CaKar3/Vik1 exhibits weaker overall MT-binding affinity and lower ATPase activity. Preliminary investigations using a multiple motor motility assay indicate CaKar3/Vik1 may not be motile. Using a maltose binding protein tagging system, we determined the X-ray crystal structure of the CaKar3 motor domain and observed notable differences in its nucleotide-binding pocket relative to ScKar3 that appear to represent a previously unobserved state of the active site. Together, these studies broaden our knowledge of novel kinesin motor assemblies and shed new light on structurally dynamic regions of Kar3/Vik1-like motor complexes that help mediate mechanical coordination of its subunits.

Subjects/Keywords: Filamentous Fungus ; Kinesin-14 ; Kar3 ; Candida Albicans ; Switch Elements ; Maltose Binding Protein ; Microtubule Motor Protein ; ATPase activity

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Delorme, C. (2012). Structural and Functional Characterization of a Novel Heterodimeric Kinesin in Candida albicans . (Thesis). Queens University. Retrieved from http://hdl.handle.net/1974/7023

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Delorme, Caroline. “Structural and Functional Characterization of a Novel Heterodimeric Kinesin in Candida albicans .” 2012. Thesis, Queens University. Accessed November 27, 2020. http://hdl.handle.net/1974/7023.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Delorme, Caroline. “Structural and Functional Characterization of a Novel Heterodimeric Kinesin in Candida albicans .” 2012. Web. 27 Nov 2020.

Vancouver:

Delorme C. Structural and Functional Characterization of a Novel Heterodimeric Kinesin in Candida albicans . [Internet] [Thesis]. Queens University; 2012. [cited 2020 Nov 27]. Available from: http://hdl.handle.net/1974/7023.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Delorme C. Structural and Functional Characterization of a Novel Heterodimeric Kinesin in Candida albicans . [Thesis]. Queens University; 2012. Available from: http://hdl.handle.net/1974/7023

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.