Signal Integration and Developmental Control via Multistep

Signal Integration and Developmental Control via Multistep Phosphorelay Signaling in Plants Jan HejátkoResearch Group Leader

Bratislava, Sep 14 2018

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Outline

Multistep Phosphorelay - Not Only CytokininSignaling in Plants

CKI1 Controls both Gametophyte andSporophyte Development in Arabidopsis

Light – Regulated Expression of CKI1Modulates Cytokinin Sensitivity

Structural Determinants of MSP SignalingSpecificity in Plants

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Signal Transduction via MSP

NUCLEUS

PM

AHK Sensor Histidine Kinases• AHK2 • AHK3• AHK4

REGULATION OF TRANSCRIPTION

INTERACTION WITH EFFECTOR PROTEINS

HPt Proteins• AHP1-6

Response Regulators• ARR1-24

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Complexity in MSP Signaling

AHK2, AHK3, AHK4

AHP1-6

CKI1

NUCLEUS

CONST.ACTIVE

Hwang and Sheen , Nature (2001)Hejátko et al., Plant Cell (2009)

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Outline

Multistep Phosphorelay - Not Only CytokininSignaling in Plants

CKI1 Controls both Gametophyte andSporophyte Development in Arabidopsis

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CKI1 Regulates Female Gametophyte Development

CKI1/CKI1CKI1/cki1-i

Hejátko et al., Mol Genet Genomics (2003)

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CKI1 cki1-i

CKI1 Regulates Female Gametophyte Development

Hejátko et al., Mol Genet Genomics (2003)

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FG0-FG1FG0-FG1FG0-FG1FG3-FG4FG3-FG4FG3-FG4

FG4-FG5FG4-FG5FG4-FG5FG7FG7FG7

Hejátko et al., Mol Genet Genomics (2003)

CKI1 is Expressed Throughout Megagametogenesis

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CKI1 is Active in Arabidopsis Gametophyte and Sporophyte

Hejátko et al., Plant Cell (2009)

αCKI1RD

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CKI1 Regulates Arabidopsis Vascular Stem Cell Activity

Hejátko et al., Plant Cell (2009)

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Complexity in MSP Signaling

AHK2, AHK3, AHK4

AHP1-6

CKI1

NUCLEUS

CONST.ACTIVE

CKI1

X ?

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Outline

Multistep Phosphorelay - Not Only CytokininSignaling in Plants

CKI1 Controls both Gametophyte andSporophyte Development in Arabidopsis

Light – Regulated Expression of CKI1Modulates Cytokinin Sensitivity

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Automated Microscopy Screening

Dobisova and Hejatko, , Methods in Mol Biol, 2014

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LPH Controls Expression of CKI1

Dobisova et al., Plant Physiol, 2017

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lph is novel allele of HEME OXYGENASE 1

Dobisova et al., Plant Physiol, 2017

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lph is Novel Allele of HEME OXYGENASE 1

Terry et al., Biochem Soc Trans, 2002

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Light Controls Spatiotemporal Specificity of CKI1 Expression

Dobisova et al., Plant Phys, 2017

WT

Short Day

Darkness

Red

Far-Red

lph/hy1-7

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CKI1 is Direct Target of Light Sensor phyA

Dobisova et al., Plant Phys, 2017

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CKI1 acts Downstream of phyA

Dobisova et al., Plant Phys, 2017

WT

Short Day

Darkness

Red

Far-Red

phyA

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Does Light-Controlled CKI1 Modulate Cytokinin Signaling?

AHK2, AHK3, AHK4

AHP1-6

CKI1

NUCLEUS

CONST.ACTIVE

CKI1

LIGHT ?

D’Agostino et al., Plant Physiology (2000)

ARRs-A

REGULATION OF TRANSCRIPTION

21Dobisova et al., Plant Physiol, 2017

Light-Regulated CKI1 Expression Controls Cytokinin Signaling

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Light Controls Root Sensitivity to Cytokinins

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Model for light- and development-specific regulation of CKI1

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Outline

Multistep Phosphorelay - Not Only CytokininSignaling in Plants

CKI1 Controls both Gametophyte andSporophyte Development in Arabidopsis

Light – Regulated Expression of CKI1Modulates Cytokinin Sensitivity

Structural Determinants of MSP SignalingSpecificity in Plants

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The results are unpublished, sorry for not showing them in the pdf version of the presentation.

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Conclusions

MSP signaling integrates several signalingpathways of both intrinsic and environmentalorigin

Although MSP displays partial promiscuity,certain specificity is retained

Signaling specificity is determined at the level ofHK receiver domain and HPt protein structure

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AcknowledgementsCEITEC and National Centre forBiomolecular Research, MasarykUniversityFunctional Genomics and Proteomics ofPlantsSiarhei DabravolskiOksana DegtjarikTereza DobisováRadka DopitováZuzana GelováRomana HejátkováJakub HorákVendula HrdinováEliška NejedláBlanka PekárováMarkéta PernisováAgnieszka SzmitkowskaMarkéta Žďárská

Biomolecular NMR SpectroscopyLubomír JandaJozef HritzZuzana JaseňákováOlga Třísková/OtrusinováLukáš ŽídekVladimír Sklenář

X-ray CrystallographyJaromír MarekTomáš Klumpler

University of South Bohemia andAcademy of Sciences of the CzechRepublic. Nové Hrady Oksana Degtjarik Michal Kutý David Řeha Ivana Smatanová-Kutá

VIB Gent and IST Austria Eva Benková Candela Cuesta

University Tuebingen Klaus Harter Michael Heunemann

CALTECH Elliot Meyerowitz Paul Tarr

Thank you for your attention

Central European Institute of TechnologyMasaryk UniversityKamenice 753/5 625 00 Brno, Czech Republic

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