Queen's University - Utility Bar

QSpace at Queen's University >
Graduate Theses, Dissertations and Projects >
Queen's Graduate Theses and Dissertations >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1974/7023

This item is restricted and will be released 2017-03-01.

Title: Structural and Functional Characterization of a Novel Heterodimeric Kinesin in Candida albicans

Files in This Item:

File Description SizeFormat
Delorme_Caroline_MJ_201202_MSc.pdf3.51 MBAdobe PDFView/Open
Keywords: Filamentous Fungus
Candida Albicans
Switch Elements
Maltose Binding Protein
Microtubule Motor Protein
ATPase activity
Issue Date: 1-Mar-2012
Series/Report no.: Canadian theses
Abstract: 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.
Description: Thesis (Master, Biochemistry) -- Queen's University, 2012-02-29 17:15:03.654
URI: http://hdl.handle.net/1974/7023
Appears in Collections:Queen's Graduate Theses and Dissertations
Biochemistry Graduate Theses (July 2007 - Sept 2016)

Items in QSpace are protected by copyright, with all rights reserved, unless otherwise indicated.


  DSpace Software Copyright © 2002-2008  The DSpace Foundation - TOP