Lipidome remodeling during cold acclimation is controles by plasma membrane associated synaptotagmins

(1)

CORTICAL ER – PM

CONTACT SITES IN PLANTS

Where Cell Biology meets abiotic

stress tolerance

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• The ER requires physical interactions with different organelles to be fully functional.

• cER interacts with PM through membrane contact sites: ER-PMCS.

• The establishment and the functions of this ER-PMCS are unknown in plants.

Abel Rosado

(3)

cER – PM Contact Sites (ER-PMCS)

• Close apposition between cER and PM

• 10-30 nm distance between membranes PM

CW

cER

cER-PM Contact Site (ER-PMCS)

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N TM SMP C2 C2 C2 C2 C2 C2 C

Yeast : Tricalbins

ER-PMCS establishment relies on Ca+2_-dependent

phospholipid binding proteins

N TM SMP C2 C2 C2 _C

Mammals : Extended Synaptotagmins

N TM SMP C2 C2 _C

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C

TM

C2 C2

Ca2 +

cER

Ca2+

PM

PIP2

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PM PIP2 PIP2 N C TM

C2 C2

cER

Ca2

+ Ca+ 2

New ER-PMCS

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Are Arabidopsis SYTs localized in ER-PMCS?

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SYT1 is closely associated to the cortical ER

Pérez-Sancho et al., Unpublished

HDEL:GFP SYT1-TRITC Overlay

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SYT1 and cortical microtubules signals are mutually exclusive

MAP4-GFP SYT1-TRITC Overlay

Overlay SYT1-TRITC

TUA6-GFP MAP4-GFP SYT1-TRITC Overlay

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Different SYTs are located in plasmodesmata

35S::SYT3-GFP

Propidium Iodide SYT1::SYT1-GFP Overlay Propidium Iodide 35S::SYT3-GFP Overlay SYT1::SYT1-GFP

SYTs localization in plants is

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Known functions of ER-PMCS in yeast and mammals

1. Ca2+_homeostasis

2. Lipid homeostasis

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syt1 has altered Ca+2_{sensitivity under stress conditions}

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syt1 has altered Ca+2_{sensitivity under stress conditions}

SYT1 might be involved Ca2+_homeostasis

during stress episodes.

Schapire et al., 2008 Plant Cell

FDA FM4-64

MS 100mM NaCl 3mM Ca2+

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(17)

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PG 32:0 PG 32:1 (1) PG 32:1 (2) PG 32:2 (2) PG 34:0 PG 34:1 (1) PG 34:1 (2) PG 34:2 (1) PG 34:2 (2) PG 34:3 (1) PG 34:3 (2) PG 34:4 (1) PG 34:5 (2) PG 36:2 PG 36:3 PG 36:4 (1) PG 36:4 (2) PG 36:5 (1) PG 36:5 (2) PG 36:6 PG 36:7

<12 8 4 3 2 1.5 1 1.5 2 2.5 3 3.5 5 10 >15 Lipid profile is altered in syt1

Fold accumulation Fold Reduction PI 34:2 PI 34:3 PI 36:5 PI 36:6

Col syt1

Rosado et al., Unpublished

(19)

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The syt1 lipid changes are associated with cold stress sensitivity

Col syt1 Col syt1

Untreated Cold Stressed

Cold Treatment

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Are Arabidopsis SYTs the orthologs of tricalbins and extended synaptotagmins?

 SYT1 has the proper subcellular localization.

 SYT1 has equivalent functions.

• It is required for Ca2+_{and lipid}

homeostasis.

• It binds phospholipids.

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CIB-CSIC Madrid

Carlos Perea Julio Salinas

Universidad de Málaga

Abel Rosado Arnaldo Schapire Miguel Ángel Botella

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(24)

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Results

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SYT1 B

INDING

TO

PS: C

A

+2

D

EPENDENCY

Schapire et al., 2008. Plant Cell

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- -

-

- -

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Ca+2 Ca+2 Ca+2 C2A C2B C2A C2B Results

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Results

Biochemical Properties of the Arabidopsis Synaptotagmin1 (SYT1)

SYT1 Binding to PS: Ionic Competition

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SYT1 binds PtdIns(P)s and PGs in a Ca+2 _{independent manner}