Molecular factors controlling plant organelle movement and positioning

  • Chiara Perico

Student thesis: Doctoral ThesisDoctor of Philosophy (PhD)

Abstract

Plant cell organelles are highly motile and their positioning plays key
roles in plant growth and development and responses to changing
environmental conditions. Movement of organelles relies on the actin
cytoskeleton and on myosins, the associated motor proteins. Myosins are
suggested to bind to receptors and adaptors on organelle membranes
allowing them to move on actin filaments in a step-wise manner. Despite
controlling the dynamics of several organelles, the myosins and myosin
receptors identified so far in Arabidopsis thaliana generally do not localise
to the organelles whose movement they control, raising the issue of how
specificity is determined. Our group have isolated a family of potential
myosin receptors (MyoB). Here I show that unlike other members from
the same family, the myosin receptor AtMRF7 specifically localises to
Golgi due to the targeting information contained within its C-terminal
region. MRF7 causes the class XI myosins known to affect Golgi
movement, XI-K and MYA1, to relocate to the Golgi, linking these
myosins for the first time to a specific compartment. MRF7 doesn’t affect
the localisation of a myosin not linked to Golgi dynamics. Furthermore,
FRET-FLIM confirmed the in vivo interaction between MRF7 and the
myosin XI-K globular tail, showing this interaction takes place via the
MRF7 N-terminal predicted myosin binding domain, DUF593. I also
show that the full-length and truncated constructs of MRF7 affect, to
different extents, Golgi and peroxisome dynamics. This study provides
evidence that myosins from class XI can localise to organelles whose
movement they control. I present a model for Golgi dynamics driven by a
heterogeneous myosin population regulated through adaptor/receptor
complexes.
Date of Award23 Jan 2020
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorImogen A Sparkes (Supervisor)

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