title: A closer look at Schizosaccharomyces pombe interphase microtubule arrays
creator: Roque, Hélio
subject: ddc-570
subject: 570 Life sciences
description: Determination of cell shape is an essential mechanism for cells like neurons, epithelial and fungal. In general, these cells are able to control their shape by positioning mechanisms that regulate cell growth and cell polarity. One key element for such a process is the microtubule cytoskeleton, which is organized into higher order assemblies in polarized cells. Therefore, an important question is to understand how these assemblies are established and maintained during interphase. We addressed this question by making use of mutants of the fission yeast Schizosaccharomyces pombe to study the organization of Interphase Microtubule Assemblies in high ultra-structural detail, using a new emerging technology – electron tomography. Mto1p, Ase1p and Klp2p are key Microtubule Associated Proteins required for the organization of microtubules into interphase microtubule arrays (IMAs). We reconstructed high resolution 3D volumes of mto1, ase1 and klp2 deletion strains (and all double mutants) in order to study the formation and organization of IMAs. We show that all mutants lacking ase1 maintain microtubule overlap regions but with altered inter-microtubule spacing. In addition, in ase1Δ klp2Δ cells the microtubules appear to have lost their connection to the spindle pole body. Interphase microtubule arrays in klp2Δ cells are mostly composed of only two microtubules instead of 2 to 9 in wild type. A similar phenotype is found in cells lacking Mto1p protein and cells lacking Mto1p and Klp2p proteins. Cells lacking Ase1p and Mto1p proteins form an interphase microtubule arrays composed of three microtubules, which extend the whole cell length. Both mto1Δ and mto1Δ ase1Δ cells present intra-nuclear microtubules but with a different organization. Finally, we show that impaired interphase microtubule arrays affect the mitochondria network structure in these deletion strains. The electron tomography analysis of the Ase1p deletion strains suggest the existence of other putative proteins involved in the microtubule bundling process. We show that most microtubules ends in mto1Δ cells have open end structures allowing microtubules to show treadmilling behavior. Furthermore, cells lacking Mto1p and/or Klp2 show IMAs with only two MTs, suggesting a role of Klp2p in microtubule nucleation. We propose a mechanistic model to tentatively explain the formation of stable IMAs. Finally we discussed the effects of defective IMAs at the cellular level by showing how the mitochondria network is affected in the deletion mutants compared with wild type cells.
date: 2008
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/9024/1/Helio_Roque_Dissertation_final.pdf
identifier: DOI:10.11588/heidok.00009024
identifier: urn:nbn:de:bsz:16-opus-90245
identifier:   Roque, Hélio  (2008) A closer look at Schizosaccharomyces pombe interphase microtubule arrays.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/9024/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng