title: Putative osmosensor--OsHK3b--a histidine kinase protein from rice shows high structural conservation with its ortholog AtHK1 from Arabidopsis.
abstract: Prokaryotes and eukaryotes respond to various environmental stimuli using the two-component system (TCS). Essentially, it consists of membrane-bound histidine kinase (HK) which senses the stimuli and further transfers the signal to the response regulator, which in turn, regulates expression of various target genes. Recently, sequence-based genome wide analysis has been carried out in Arabidopsis and rice to identify all the putative members of TCS family. One of the members of this family i.e. AtHK1, (a putative osmosensor, hybrid-type sensory histidine kinase) is known to interact with AtHPt1 (phosphotransfer proteins) in Arabidopsis. Based on predicted rice interactome network (PRIN), the ortholog of AtHK1 in rice, OsHK3b, was found to be interacting with OsHPt2. The analysis of amino acid sequence of AtHK1 showed the presence of transmitter domain (TD) and receiver domain (RD), while OsHK3b showed presence of three conserved domains namely CHASE (signaling domain), TD, and RD. In order to elaborate on structural details of functional domains of hybrid-type HK and phosphotransfer proteins in both these genera, we have modeled them using homology modeling approach. The structural motifs present in various functional domains of the orthologous proteins were found to be highly conserved. Binding analysis of the RD domain of these sensory proteins in Arabidopsis and rice revealed the role of various residues such as histidine in HPt protein which are essential for their interaction.
authors.affiliation: a Synthetic Biology and Biofuel Group , International Center for Genetic Engineering and Biotechnology , New Delhi 110067 , India .
authors.forename: Hemant Ritturaj
authors.initials: HR
authors.lastname: Kushwaha
authors.forename: Sneh Lata
authors.initials: SL
authors.lastname: Singla-Pareek
authors.forename: Ashwani
authors.initials: A
authors.lastname: Pareek
mesh_terms: D029681:Arabidopsis Proteins / Q000737:chemistry*; D020134:Catalytic Domain; D027682:Cation Transport Proteins / Q000737:chemistry*; D017124:Conserved Sequence; D000071677:Histidine Kinase; D008958:Models, Molecular; D012275:Oryza / Q000201:enzymology*; D010766:Phosphorylation; D010940:Plant Proteins / Q000737:chemistry* / Q000378:metabolism; D011494:Protein Kinases / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary; D040681:Structural Homology, Protein; D027981:Symporters / Q000737:chemistry*
chemical_list: D029681:Arabidopsis Proteins; D027682:Cation Transport Proteins; C490286:HKT1 protein, Arabidopsis; D010940:Plant Proteins; D027981:Symporters; D011494:Protein Kinases; D000071677:Histidine Kinase
keywords: CHASE domain; histidine kinase; histidine phosphotransfer protein; receiver domain; transmitter domain; two component system