title: OsHsfA2c and OsHsfB4b are involved in the transcriptional regulation of cytoplasmic OsClpB (Hsp100) gene in rice (Oryza sativa L.).
abstract: ClpB-cytoplasmic (ClpB-cyt)/Hsp100 is an important chaperone protein in rice. Cellular expression of OsClpB-cyt transcript is governed by heat stress, metal stress, and developmental cues. Transgenic rice plants produced with 2 kb OsClpB-cyt promoter driving Gus reporter gene showed heat- and metal-regulated Gus expression in vegetative tissues and constitutive Gus expression in calli, flowering tissues, and embryonal half of seeds. Rice seedlings regenerated with OsClpB-cyt promoter fragment with deletion of its canonical heat shock element sequence (HSE(-273 to -280)) showed not only heat shock inducibility of Gus transcript/protein but also constitutive expression of Gus in vegetative tissues. It thus emerges that the only classical HSE present in OsClpB-cyt promoter is involved in repressing expression of OsClpB-cyt transcript under unstressed control conditions. Yeast one-hybrid assays suggested that OsHsfA2c specifically interacts with OsClpB-cyt promoter. OsHsfA2c also showed binding with OsClpB-cyt and OsHsfB4b showed binding with OsClpB-cyt; notably, interaction of OsHsfB4b was seen for all three OsClpB/Hsp100 protein isoforms (i.e., ClpB-cytoplasmic, ClpB-mitochondrial, and ClpB-chloroplastic). Furthermore, OsHsfB4b showed interaction with OsHsfA2c. This study suggests that OsHsfA2c may play a role as transcriptional activator and that OsHsfB4b is an important part of this heat shock responsive circuitry.
authors.affiliation: Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi 110021, India.
authors.forename: Amanjot
authors.initials: A
authors.lastname: Singh
authors.forename: Dheeraj
authors.initials: D
authors.lastname: Mittal
authors.forename: Dhruv
authors.initials: D
authors.lastname: Lavania
authors.forename: Manu
authors.initials: M
authors.lastname: Agarwal
authors.forename: Ratnesh Chandra
authors.initials: RC
authors.lastname: Mishra
authors.forename: Anil
authors.initials: A
authors.lastname: Grover
mesh_terms: D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D012275:Oryza / Q000235:genetics* / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D000076249:Heat Shock Transcription Factors; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D014157:Transcription Factors