High impact information on CKI1

• Functional screening of an Arabidopsis cDNA library enabled the identification of a novel cDNA, ESR1 (for Enhancer of Shoot Regeneration), that can confer cytokinin-independent shoot formation when overexpressed in Arabidopsis root explants [1].
• We hypothesized that proteins that interact with histidine kinases throughout evolution may represent partners for Nm23-H1 and focused on the interaction of Arabidopsis "two-component" histidine kinase ERS with CTR1 [2].
• Fourteen genes encode 22 putative histidine kinases with a conserved histidine and other typical histidine kinase signature sequences, five phosphotransfer genes encoding seven phosphotransfer proteins, and 32 response regulator genes encoding 44 proteins [3].
• We report that a major cue for the negative regulation of sulfur acquisition is executed by cytokinin response 1 (CRE1)/wooden leg (WOL)/Arabidopsis histidine kinase 4 (AHK4) cytokinin receptor in Arabidopsis root [4].
• We identified four histidine kinase (HK) genes of a cytokinin receptor family, two histidine-containing phosphotransmitter (HPt) genes, thirteen A-type response regulator (RR) genes and six B-type RR genes in the rice genome [5].

Biological context of CKI1

• A full length cDNA (CrCKR1) encoding a hybrid histidine kinase was isolated from a Catharanthus roseus cDNA library [6].
• While the T-DNA insertion mutant (arr15-1) showed no apparent phenotype, the cytokinin-independent overexpression of ARR15 in ARR15-ox plants resulted in a reduced sensitivity toward exogenously applied cytokinin, not only in elongation of roots in plants, but also in green callus formation (or shoot formation) in explants [7].

Anatomical context of CKI1

• Each system generally consists of a sensor protein histidine kinase, which is anchored in the cell membrane, and a cytoplasmic response regulator, whose activity is modulated by the sensor [8].

Associations of CKI1 with chemical compounds

• In this study, we characterized, in vitro, the putative cytokinin-responsive CKI1 His-kinase, in terms of His-Asp phosphorelays [9].
• Recent information on the structure and role of six different putative ethylene receptors in tomato is discussed, including evidence supporting the receptor inhibition model for ripening, possible differences in histidine kinase activity between receptors, and the importance of receptor LeETR4 in ripening [10].

Regulatory relationships of CKI1

• AHK3 suppresses a sensor histidine kinase mutant of yeast [11].

Other interactions of CKI1

• We previously identified a set of structurally related genes, AHK2, 3 and 4, each encoding a sensor histidine kinase in Arabidopsis thaliana [12].

References