Functional characterisation of the two-component signalling system of Arabidopsis

The objective of the proposal is to study specific aspects of the function of the two-component signalling system (TCS) in Arabidopsis. The TCS is, among the higher eukaryotes, unique to plants. Arabidopsis harbours eight hybrid sensor kinases (AHKs), five histidine phosphotransfer proteins (AHPs) and 22 genes encoding two different types of response regulators (type A and type B ARR genes). Most of the functions of members of the TCS, in particular in which signalling pathway they participate and how they realize information transfer via interactions with other proteins of Arabidopsis and through gene activation are unknown. We will contribute to an improved understanding of the TCS in two ways. We have cloned and expressed most of the TCS genes in order to identify protein-protein interactions between proteins of the TCS and other proteins of the Arabidopsis proteome by means of two-hybrid screens and affinity co-purification coupled with mass spectrometry. By genome-wide expression analysis we have identified a set of immediate early response genes to cytokinin, which signals through the TCS. These will serve, beside a general phenotypical analysis, as endogenous reporter genes to characterize single and multiple cytokinin receptor knockout mutants and lines expressing gain-of-function and dominant-negative TCS proteins in order to identify individual TCS pathways.

Arabidopsis genes coding for proteins of the two component system.

Gene names

Chromo- some

MIPS designation

Accession no. (cDNA)

Full length cDNA cloned or RT-cDNA PCR product

Arabidopsis sensor histidine kinase gene family (AHK)¹

CRE1 (AHK4)	2	At2g01830	AB049934	Cloned
AHK2	5	At5g35750	AB046869	Cloned
AHK3	1	At1g27320	AB046870	PCR product
CKI1	2	At2g47430	D87545	-
CKI2 (AHK5)	5	At5g10720	18426882	-
ATHK1	2	At2g17820	AB010914	Cloned
ETR1	1	At1g66340	L24119	-
ERS1	2	At2g40940	U21952	PCR product

Arabidopsis histidine phosphotransfer protein gene family (AHP)²

AHP1	3	AT3g21510	AB015141	Cloned
AHP2	1	AT3g29350	AB015142	Cloned
AHP3	5	AT5g39340	AB015143	Cloned
AHP4	3	AT3g16360	AB041766	PCR product
AHP5	1	At1g03430	AB041767	Cloned

Arabidopsis type A response regulator genes (type A ARR)³

ARR3	1	At1g59940	AB008486	Cloned
ARR4(ATRR1)	1	At1g10470	AB008487	Cloned
ARR5(ATRR2)	3	At3g48100	AB008488	Cloned
ARR6	5	At5g62920	AB008489	Cloned
ARR7	1	At1g19050	AB008490	Cloned
ARR8 (ATRR3)	2	At2g41310	AB010917	Cloned
ARR9 (ATRR4)	3	At3g57040	AB010918	Cloned
ARR15	1	At1g74890	AF305720	Cloned
ARR16	2	At2g40670	AF305721	Cloned
ARR17	3	At3g56380	AF305722	PCR product
ARR22	3	At3g04280	AC016880	PCR product

Arabidopsis type B response regulator genes (type B ARR)

ARR1	3	At3g16855 At3g16857	AB028608 AB001308	Cloned
ARR2	4	At4g16110	AB016472	Cloned
ARR10 (ARLP2)	4	At4g31920	AJ005195	Cloned
ARR11(ARLP1)	1	At1g67710	AJ005194	Cloned
ARR12	2	At2g25180	AC018722	PCR product
ARR13	2	At2g27070	AC005623	-
ARR14	2	At2g01760	AC006069	Cloned
ARR18	5	At5g58080	AB024029	PCR product
ARR19	1	At1g49190	AC016041	-
ARR20	3	At3g62670	AL162651	Cloned
ARR21	5	At5g07210	AL163652	-

1Three members of the ethylene receptor gene family (ETR2, ERS2, EIN4) and the phytochromes PHYA, PHYB, PHYC, PHYD, PHYE do not contain the canonical His-kinase motifs and were not listed. 2One pseudo phosphotransfer protein was not listed. 3Nine pseudo-response regulator genes (APRR1 APRR9) were not listed.

Literature:
Heyl, A., Schmülling, T. (2003) Cytokinin signal perception and transduction. Curr. Op. Plant Biol. 6, 480-488.

 

Prof. Dr. Thomas Schmülling
Freie Universität Berlin
Institut für Biologie/Angewandte Genetik
Albrecht-Thaer-Weg 6
D-14195 Berlin
Germany

Telefon            030-8385 5808
Sekretariat       030-8385 5801
Fax                  030-8385 4345

email tschmue@zedat.fu-berlin.de