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TOBFAC: The database of tobacco transcription factors

Family: GARP-ARR-B

Minimum number of tobacco GARP-ARR-B genes: 11

Count of tobacco GARP-ARR-B sequences: 18

Pfam accession:

In Arabidopsis thaliana, a Histidine-to-Aspartate (His-->Asp) phosphorelay is involved in the signal transduction for propagation of certain stimuli, such as plant hormones. Through the phosphorelay, the type-B phospho-accepting response regulator (ARR) family members serve as DNA-binding transcriptional regulators, whose activities are most likely regulated by phosphorylation/dephosphorylation .

The Arabidopsis genome codes for 22 response regulators (ARRs), 12 of which contain a Myb-like DNA binding domain called ARRM (type B). The remainder (type A) possess no apparent functional unit other than a signal receiver domain containing two aspartate and one lysine residues (DDK) at invariant positions, and their genes are transcriptionally induced by cytokinins without de novo protein synthesis. The type B members, ARR1 and ARR2, bind DNA in a sequence-specific manner and work as transcriptional activators.

Here we present evidence that ARR1 mediates a cytokinin signal, probably through its NH2-terminal signal receiver domain, and transactivates ARR6, which is immediately responsive to cytokinins. A paralogous response regulator, ARR2, shows almost identical characteristics to ARR1, suggesting a functional overlap. Residual cytokinin responses observed with the arr1-1 mutant may have been provided by ARR2. In addition to ARR6, other type A member genes, including ARR4, ARR5, ARR7, ARR8, and ARR9, were also activated by DEX at various levels in 35S::ARR1DDK::GR plants, suggesting that all the immediate cytokinin-responsive genes belonging to this group are directly activated by ARR1. Also, other cytokinin-responsive genes whose promoter regions contain the ARR1 recognition sequences are possibly transactivated by ARR1. A screening for ARR1 target genes using transgenic 35S::ARR1-DDK::GR plants will shed light on the whole view of the early cytokinin signal transduction pathway. We conclude that ARR1 is a principal transcription factor-type response regulator that is involved in an early step of cytokinin signal transduction, possibly as a partner of the sensor histidine kinase CRE1 .

Homologs of bacterial two-component signal transduction elements are emerging as key players in eukaryotic signaling systems. The recent identification of a large gene family in Arabidopsis that is similar to two-component response regulators emphasizes the importance of this signaling mechanism in plants. The understanding of the function of these response regulator genes is only rudimentary but the transcriptional induction of a subset by cytokinin suggests a role for some of these regulators in the response to this important plant hormone .

Papers

Aoyama, T; Oka, A. Cytokinin signal transduction in plant cells. J. Plant Res. 2003. 116(3):221-31 PMID: 12836044

D'Agostino, IB; Kieber, JJ. Phosphorelay signal transduction: the emerging family of plant response regulators. Trends Biochem. Sci. 1999. 24(11):452-6 PMID: 10542414

Kakimoto, T. Perception and signal transduction of cytokinins. Annu Rev Plant Biol 2003. 54:605-27 PMID: 14503005

Number of contigs: 34

Number of singlets: 69

Number of genes with first 26 amino acids – 7

Number of genes with 50 aa – 72 aa – 2

Number of genes with 27 aa to the end – 4

Number of genes with 35 aa – 72 aa – 1

Number of genes with 27 aa – 65 aa – 3

Number of full – 1

Total minimum number – 11

Search sequences and info

Transcription factor sequences

Tobacco published genes related to transcription factor family GARP-ARR-B

Authors of this site:

Paul J Rushton
Marta T. Bokowiec
Xianfeng (Jeff) Chen
Thomas (Tom) W Laudeman
Jennifer F. Brannock
Michael P. Timko

Contact:

pr8y@virginia.edu