Histidine-containing phosphotransfer (HPt) signal transducers implicated in His-to-Asp phosphorelay in Arabidopsis.
His to Asp phosphorelay signal transduction mechanisms involve three types of widespread signaling components: a sensor His-kinase, a response regulator, and a histidine-containing phosphotransfer (HPt) domain. In Arabidopsis, several sensor His-kinases have recently been discovered (e.g., ETR1 and CKI1) through extensive genetic studies. Furthermore, a recent search for response regulators in this higher plant revealed that it possesses a group of response regulators (ARR-series), each of which exhibits the phospho-accepting receiver function. However, no signal transducer containing the HPt domain has been reported. Here we identify three distinct Arabidopsis genes (AHP1 to AHP3), each encoding a signal transducer containing a HPt domain. Both in vivo and in vitro evidence that each AHP can function as a phospho-transmitting HPt domain with an active histidine site was obtained by employing both the Escherichia coli and yeast His-Asp phosphorelay systems. It was demonstrated that AHP1 exhibits in vivo ability to complement a mutational lesion of the yeast YPD1 gene, encoding a typical HPt domain involved in an osmosensing signal transduction. It was also demonstrated that AHPs can interact in vitro with ARRs through the His-Asp phosphotransfer reaction. It was thus suggested that the uncovered sensors-AHPs-ARRs lineups may play important roles in propagating environmental stimuli through the multistep His-Asp phosphorelay in Arabidopsis.
Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Japan.
T
T
Suzuki
A
A
Imamura
C
C
Ueguchi
T
T
Mizuno
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D001224:Aspartic Acid / Q000378:metabolism*; D020134:Catalytic Domain; D002874:Chromosome Mapping; D004268:DNA-Binding Proteins / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics; D017343:Genes, Plant; D005816:Genetic Complementation Test; D006639:Histidine / Q000378:metabolism*; D000071677:Histidine Kinase; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D010770:Phosphotransferases / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics
C117966:AHP1 protein, Arabidopsis; C117967:AHP2 protein, Arabidopsis; C117968:AHP3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D010940:Plant Proteins; D029701:Saccharomyces cerevisiae Proteins; D001224:Aspartic Acid; D006639:Histidine; D010770:Phosphotransferases; D011494:Protein Kinases; C102035:YPD1 protein, S cerevisiae; D000071677:Histidine Kinase