Download Plasma Membrane/ Cell Wall Continuum

Plasma Membrane - Cell Wall
Continuum
PCDU Seminar 2015
Stella Eggels
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Contents
• Importance of PM-CW-interactions
• PM-related cell wall synthesis
• PM-CW connections
– Proteins involved in connections
• Cytoskeleton-PM-CW Continuum: Signaling
• Endocytosis of pectins
– Cytokinesis
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Importance of PM-CW-interactions
• growth and cell expansion:
– CW synthesis & remodeling is PM-related
– structure of one depends on the other
– formation of a cell plate
• adaptation to environmental stimuli:
– exchange of substances
– transduction of signals at CW by PM-proteins
• cell to cell interactions
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PM-related cell wall synthesis
– membrane composition affects
location of CSC
 motility of CSC
 rate of cellulose synthesis
quizlet.com/10254227/plants-ch-15taiz-flash-cards/
• transmembrane Cellulose synthase complexes (CSC):
• other components: ER/Golgi  PM-mediated secretion
• endocytosis & recycling important for PM- & CWproduction
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PM-CW connections
• close contact due to turgor pressure
• direct, physical connections: Hechtian strands
– esp. at plasmodesmata
– cellulose microfibrils directly or indirectly involved
– different groups of proteins
• PM-CW-junctions barriers against pathogen attacks
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kimjy.gnu.kr/Lec%20Plant%20Cell%20Biol/1-Membranous%20organelles-session1.files/frame.htm
Liu et al., 2015
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Proteins involved in connections
RGD-binding proteins
• RGD: amino acid sequence of extracellular adhesive
glycoproteins
• needed for Hechtian strand formation
• e.g. NDR1: RGD-like recognition motif,
transmembrane domain, GPI anchor
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GPI-anchored proteins (GAPs)
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GPI: surface anchor for apoplastic proteins
can be released into CW
e.g. COBRA
Arabinogalactan proteins (AGPs)
– decoration attached to CW matrix polysaccharides
• Fasciclin-like AGPs
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Plasma membrane receptors
• Receptor-like kinases (RLK)
• extracellular domains interact
with CW-components
• e.g. WAKs (wall associated kinases):
bind apoplastic pectins
PM-CW linker proteins and signaling:
• mechanical, osmotic & pathogen stress
cytoskeletal or hormonal responses
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Cytoskeleton-PM-CW Continuum: Signaling
• Mechanical signals sensed by linkers
 communication with cytoskeleton (esp. Actin)
 affect growth, differentiation, shape, cell - cell communication
WAKs (+ pectins):
• cytoplasmic kinase domain
• B, Al bind pectin and affect cytoskeleton
• receptors for endocytosis of adhesive CW pectins
AGPs
• bind to pectins, might interact with WAKs
• mutants multiple CW-related defects
Formins, Myosin VIII + Callose-Synthase
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Handbook of Plant Science, Vol.1, Keith Roberts
Endocytosis of pectins
• BFA  formation of dense vesicle compartments in meristematic root cells
• contain pectins of inner CW-side & recycling PMproteins  endocytotic origin, recycling of
pectins
Baluska et al. 2002
H+-ATPase
PIN1
RGII-borate pectins
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• possible effects of pectin endocytosis:
– CW integrity affected
 growth, polarization, morphogenesis?
– pectin based signaling
– role in turnover of pectins in dividing cells
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Cytokinesis
• initiation and expansion of cell plate by fusion of endosomes
with CW and PM material
• eventually contribution of Golgi vesicles
• recycling  rapid, robust
RGII pectin
Dhonukshe et al. 2005
PIN2
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References
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Baluška, F. et al. (2003). Cytoskeleton-Plasma Membrane-Cell Wall Continuum in
Plants . Emerging Links Revisited. Plant Phyiology, 133(October), 482–491.
Dhonukshe, P. et al. (2006). Endocytosis of Cell Surface Material Mediates Cell
Plate Formation during Plant Cytokinesis. Developmental Cell, 10(1), 137–150.
Liu, Z. et al. (2015). At the border: the plasma membrane-cell wall continuum.
Journal of Experimental Botany, 66(6), 1553–1563.
Palme, K. et al. (2002). F-actin-dependent endocytosis of cell wall pectins in
meristematic root cells. Insights from brefeldin A-induced compartments. Plant
Physiology, 130(1), 422–431.
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Thank you!
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