Transcript trans-Golgi-Network

Endocytic network in plants
trans - Golgi network
Oskar Liebisch
Wednesday, 4th of November, 2015
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Structure
1.
2.
3.
4.
Where is the trans – Golgi network located?
The trans – Golgi network
Plant endosomal trafficking (EE, LE)
Signaling proteins
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http://cytochemistry.net/_Media/golgi1a_med_hr.j
peg
"Plant cell structure-en"
by LadyofHats
- Self-made
using Adobe
Illustrator.- (The
edited was
also
"Golgi apparatus
(borderless
version)-en"
by Kelvinsong
Own original
work. Licensed
under
CC BY
made by me, LadyofHats).
Licensed
under
Public
Domain
via
Commons
3.0 via Commons https://commons.wikimedia.org/wiki/File:Plant_cell_structure-en.svg#/media/File:Plant_cell_structurehttps://commons.wikimedia.org/wiki/File:Golgi_apparatus_(borderless_version)en.svg
en.svg#/media/File:Golgi_apparatus_(borderless_version)-en.svg
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TGN hypothesis
• Toyooka et al. 2009:
– TGN fuses with the PM releasing its cargo to the
extracellulare space  completely fuse with PM
• Viotti et al. 2010:
– TGN cycles between Golgi associated and free states
• Kang et al. 2011:
– Short living structure, that releases secretory and
clathrin coated vesicles, gives rise to the MVB by their
remnant membranes
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Kang et al. (2011)
• I. Golgi trans-type compartment; transformation
is coupled by the recruitment of RabA4b and its
effector protein Found
PI-4Kß1
as TGN)
in Kang(identification
et al. (2011)
• II. transformation of the trans-most Golgi cisterna
into a TGN; accompanied by 3 structural changes:
– Onset of separation of trans-most cisterna
Found in Kang et al. (2011)
– 30-35% reduction
of the cisternal membrane area
– Formation of round SV buds, which are not confined
to the trans-Golgi cisterna
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The trans – Golgi network
•
At first it was known as a subcompartment of the Golgi
BUT
•
Newest study indicating TGN to be a free, highly mobile organelle
– Early Endosome
•
Matures from the Golgi; study of Viotti et al. 2010 indicate that it can reassociate
with
– V-ATPase required for identity of TGN?
•
Characterized by associated proteins like RabA4b, PI-4k, Rab GTPase, SNARE
proteins, VHA-a1 (subunit of V-ATPase)
• Receives endocytosed cargo from PM (e.g. carbohydrates, proteins)
• biosynthetic sorting station
VHA-a1 subunit of V-ATPase marked red with Red Fluorescent Protein; found in Viotti et al.
• Forms Clathrin coated vesicles (TGN – MVB, Vacuole), secretory vesicles (TGN –
(2010)
PM)
VHA-a1 immunogold labeled in ConcA treated cells; found in Viotti et al. (2010)
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Plant endosomal trafficking pathways; found in Reyes et al. (2011)
What is an endosome?
• Compartments of the endocytic membrane
transport pathway
– From the PM to the lysosome
– From the PM to the TGN
Early endosome (EE) / Late Endosome
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Plant endosomal trafficking
Early/
After treatmemt
with
the V-ATPase
recycling endosomes
inhibitor Concanamycin A
- TGN associated with the Golgi
- Number of MVB decreased
• Tubular-vesicular structure, bearing clathrin
coated vesicles (CCV)
• First branching point for: endocytosed and
newly synthezised proteins
• Receive and recycle of:
1. endocytosed membrane
proteins; back to PM or to the MVB
2. Vacuolar cargo receptors back
to TGN
Late endosomes/
Multivesicular bodies (MVB)
•
•
•
•
Prevacuolar compartments (intermediate)
Spherical
Derived from the TGN
Sorting membrane proteins into endosomal
intraluminal vesicles (ILVs); degradation by
fusion with the tonoplast (degradation by
vacuoles/lysosomes)
• Carrying also new proteins from the Golgi
to lysosomes/vacuoles
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How does the sorting work?
Mediators
Example of function
ESCRTs (Endosomal Sorting
Complex Required for Transport)
• Transmembrane
proteins; degredation
Retromer
• Vacuolar Sorting
Receptors (VSRs)
• Extracellular secretion
(PIN protein)
Ubiquitin
• BOR1 degradation
ADP-ribosylation factor (ARF)
maschinery
• PIN and AUX1 (GNOM)
• Coating complexes and mediators
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ESCRTs
1. ESCRT-0 recognition of PI3P (Phosphatidylinositol 3-phosphate;
phospholipe in the PM, serves as binding station for some sorting
proteins) via the FYVE domain
1. Clusters cargo
• In fungi and metazoans: 4 multimeric ESCRT
2. ESCRT-1 + ESCRT-2 induce the formation of buds
related complexes have been identified to be
3. ESCRT-3 mediates vesicle fission
related to the endosomes
ESCRTs are needed to internalize proteins into the MVB (ILVs), because only
But not in plants!
the outer membrane of the MVB can fuse with the vacuole and release the
ILVs for degradation
ESCRT complex
Ortholog
0
TOM1
1
ELCH Protein
2
-
Mechanism of degradation of a PM bound protein; Found in: David Scheuring
3 not publishedCHMP1
(Dissertation 2011),
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Schematic
Retromer
Retromer
• Pentameric complex
• 9 subunits
• Sorts transmembrane proteins back from the
TGN
• Vacuolar Sorting Receptors (VSRs)
• Auxin efflux carrier (PIN family)
"Retromer protein complex" by Kianzoidlee - Using Pymol and adobe illustratorPreviously published: Used for my hon
thesis. Licensed under CC BY-SA 3.0 via Commons 12
https://commons.wikimedia.org/wiki/File:Retromer_protein_complex.png#/media/File:Retromer_protein_complex.p
Plant endosomal trafficking pathways; found in Reyes et al. (2011)
Example BOR1: Ubiquitination
Ubiquination of BOR1; found in Reyes et al. 2011
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Thank you for your attention!
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References
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Gendre D., McFarlane H.E., Johnson E., Mouille G., Sjödin A., Oh J., Levesque-Tremblay G., Watanabe Y., Samuels
L., Bhaleraoa R.P.: Trans-Golgi Network Localized ECHIDNA/Ypt Interacting Protein Complex Is Required for the
Secretion of Cell Wall Polysaccharides in Arabidopsis. The Plant Cell (2013), Vol. 25: 2633–2646.
Kang BH, Nielsen E, Preuss ML, Mastronarde D, Staehelin LA: Electron tomography of RabA4b- and PI-4Kbeta1labeled trans Golgi network compartments in Arabidopsis. Traffic (2011), 12:313-329.
Kleine-Vehn J., Dhonukshe P., Swarup R., Bennett M., Frimla J.: Subcellular Trafficking of the Arabidopsis Auxin
Influx Carrier AUX1 Uses a Novel Pathway Distinct from PIN1. The Plant Cell (2006), Vol. 18, 3171–3181.
Reyes F.C., Buono R. and Otegui M.S.: Plant endosomal trafficking pathways: Current Opinion in Plant Biology
(2011), 14: 666-673.
Šamaj J., Read N.D., Volkmann D., Menzel D., Baluška F.: The endocytic network in plants. TRENDS in Cell Biology
(2005). Vol15 No., 425-433.
Scheuring D.: Funktionelle Charakterisierung pflanzlicher Endosomen. (2011); not published.
Scheuring D., Viotti C., Krüger F., Künzl F., Sturm S., Bubeck J., Hillmer S., Frigerio L., Robinson D.G., Pimpl P.,
Schumacher K.: Multivesicular Bodies Mature form the Trans-Golgi Network/Early Endosome in Arabidopsis. The
Plant Cell (2011), Vol.23: 3463-3481.
Toyooka K, Goto Y, Asatsuma S, KoizumiM, Mitsui T, Matsuoka K: A mobile secretory vesicle cluster involved in
mass transport from the Golgi to the plant cell exterior. Plant Cell 2009, 21:1212-1229.
Viotti C, Bubeck J, Stierhof YD, Krebs M, Langhans M, van den Berg W, van Dongen W, Richter S, Geldner N,
Takano J et al.: Endocytic and secretory traffic in Arabidopsis merge in the trans-Golgi network/early endosome,
an independent and highly dynamic organelle. Plant Cell (2010), 22:1344-1357.
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