title: Characterization of 5'UTR of rice ClpB-C/Hsp100 gene: evidence of its involvement in post-transcriptional regulation.
abstract: Rice (Oryza sativa) ClpB-C (OsClpB-C) protein is expressed upon heat stress in vegetative tissues and constitutively in seeds. We produced stably transformed Arabidopsis plants carrying β-glucuronidase (Gus) reporter gene downstream to 1-kb OsClpB-C promoter (1kbPro plants). In the 1kbPro plants, expression of Gus transcript and protein followed the expression pattern of OsClpB-C gene in rice plants, i.e., heat induced in vegetative tissues and constitutive in seeds. Next, we produced transgenic Arabidopsis plants containing Gus downstream to 862-bp fragment of OsClpB-C promoter [lacking 138 nucleotides from 3' end of the 5'untranslated region (5'UTR); ∆UTR plants). In ∆UTR plants, Gus transcript was expressed in heat-inducible manner, but strikingly, Gus protein levels were negligible after heat treatment. However, Gus protein was expressed in ∆UTR seedlings at levels comparable to 1kbPro seedlings when recovery treatment of 22 °C/2 h was given post heat stress (38 °C/15 min). This suggests that 5'UTR of OsClpB-C gene is involved in its post-transcriptional regulation and is an obligate requirement for protein expression during persistent heat stress. Furthermore, the Gus transcript levels were higher in the polysomal RNA fraction in heat-stressed seedlings of 1kbPro plants as compared to ∆UTR plants, indicating that 5'UTR aids in assembly of ribosomes onto the Gus transcript during heat stress. Unlike the case of seedlings, Gus protein was formed constitutively in ∆UTR seeds at levels comparable to 1kbPro seeds. Hence, the function of 5'UTR of OsClpB-C is dispensable for expression in seeds.
authors.affiliation: Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India.
authors.forename: Ratnesh Chandra
authors.initials: RC
authors.lastname: Mishra
authors.affiliation: Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India.
authors.lastname: Richa
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.affiliation: Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India.
authors.forename: Lalit Dev
authors.initials: LD
authors.lastname: Tiwari
authors.affiliation: Department of Plant Molecular Biology, University of Delhi South Campus, New Delhi, 110021, India. anil.anilgrover@gmail.com.
authors.forename: Anil
authors.initials: A
authors.lastname: Grover
mesh_terms: D020121:5' Untranslated Regions; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D017930:Genes, Reporter; D005966:Glucuronidase / Q000235:genetics; D006360:Heat-Shock Proteins / Q000235:genetics*; D018869:Heat-Shock Response; D006358:Hot Temperature; D012275:Oryza / Q000235:genetics* / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000502:physiology; D011401:Promoter Regions, Genetic; D012639:Seeds / Q000235:genetics
chemical_list: D020121:5' Untranslated Regions; D006360:Heat-Shock Proteins; D010940:Plant Proteins; D005966:Glucuronidase
keywords: 5′UTR; Arabidopsis; ClpB-C/Hsp100; Heat stress; Rice; Seed; Vegetative tissues