title: The H1 histone variant of tomato, H1-S, is targeted to the nucleus and accumulates in chromatin in response to water-deficit stress.
abstract: Water deficit has a significant impact on patterns of gene expression. Based on the deduced amino acid sequence, it has been proposed that the drought and abscisic acid-induced gene (his1-s) of tomato (Lycopersicon esculentum Mill.) encodes an H1 histone variant. To study the role of H1-S it is important to understand the expression characteristics of the protein. To identify the his1-s product in vivo the his1-s cDNA was fused to a (His)6 tag and overexpressed in Escherichia coli. The H1-S fusion protein was used to generate an antibody that recognized a protein with an apparent molecular weight of 31 kDa that accumulates in response to water deficit in the whole plant and detached leaves. A time course of his1-s expression showed that protein accumulation is delayed compared to the mRNA accumulation in both the whole plant and detached leaves. Cellular fractionation, immunofluorescence and H1-S::beta-glucuronidase fusion analyses in transgenic tissues were used to determine the cellular localization of H1-S. The results showed that H1-S accumulates in nuclei and is associated with chromatin of wilted tomato leaves. The drought- and abscisic acid-induced gene his1-s encodes a linker-histone subtype specifically accumulated in the nuclei and chromatin of tomato leaves subjected to water-deficit conditions. Although the molecular mechanism of H1-S function is still unclear, the expression characteristics of H1-S are consistent with a potential role of this protein in the regulation of gene expression in response to water deficit.
authors.affiliation: Department of Botany and Plant Sciences, University of California, Riverside, USA.
authors.forename: G S
authors.initials: GS
authors.lastname: Scippa
authors.forename: A
authors.initials: A
authors.lastname: Griffiths
authors.forename: D
authors.initials: D
authors.lastname: Chiatante
authors.forename: E A
authors.initials: EA
authors.lastname: Bray
mesh_terms: D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000502:physiology*; D002843:Chromatin / Q000502:physiology*; D003001:Cloning, Molecular; D003890:Desiccation; D004926:Escherichia coli; D018506:Gene Expression Regulation, Plant; D005966:Glucuronidase / Q000096:biosynthesis / Q000235:genetics; D006657:Histones / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D007700:Kinetics; D018551:Solanum lycopersicum / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D018515:Plant Leaves / Q000502:physiology; D030821:Plants, Genetically Modified; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins / Q000737:chemistry; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D006657:Histones; D012333:RNA, Messenger; D018749:RNA, Plant; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D005966:Glucuronidase