title: The intrinsically disordered protein LEA7 from Arabidopsis thaliana protects the isolated enzyme lactate dehydrogenase and enzymes in a soluble leaf proteome during freezing and drying.
abstract: The accumulation of Late Embryogenesis Abundant (LEA) proteins in plants is associated with tolerance against stresses such as freezing and desiccation. Two main functions have been attributed to LEA proteins: membrane stabilization and enzyme protection. We have hypothesized previously that LEA7 from Arabidopsis thaliana may stabilize membranes because it interacts with liposomes in the dry state. Here we show that LEA7, contrary to this expectation, did not stabilize liposomes during drying and rehydration. Instead, it partially preserved the activity of the enzyme lactate dehydrogenase (LDH) during drying and freezing. Fourier-transform infrared (FTIR) spectroscopy showed no evidence of aggregation of LDH in the dry or rehydrated state under conditions that lead to complete loss of activity. To approximate the complex influence of intracellular conditions on the protective effects of a LEA protein in a convenient in-vitro assay, we measured the activity of two Arabidopsis enzymes (glucose-6-P dehydrogenase and ADP-glucose pyrophosphorylase) in total soluble leaf protein extract (Arabidopsis soluble proteome, ASP) after drying and rehydration or freezing and thawing. LEA7 partially preserved the activity of both enzymes under these conditions, suggesting its role as an enzyme protectant in vivo. Further FTIR analyses indicated the partial reversibility of protein aggregation in the dry ASP during rehydration. Similarly, aggregation in the dry ASP was strongly reduced by LEA7. In addition, mixtures of LEA7 with sucrose or verbascose reduced aggregation more than the single additives, presumably through the effects of the protein on the H-bonding network of the sugar glasses.
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany.
authors.forename: Antoaneta V
authors.initials: AV
authors.lastname: Popova
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany.
authors.forename: Saskia
authors.initials: S
authors.lastname: Rausch
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany.
authors.forename: Michaela
authors.initials: M
authors.lastname: Hundertmark
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany.
authors.forename: Yves
authors.initials: Y
authors.lastname: Gibon
authors.affiliation: Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, D-14476 Potsdam, Germany. Electronic address: hincha@mpimp-golm.mpg.de.
authors.forename: Dirk K
authors.initials: DK
authors.lastname: Hincha
mesh_terms: D017360:Arabidopsis / Q000737:chemistry*; D029681:Arabidopsis Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D003890:Desiccation; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005615:Freezing; D015870:Gene Expression; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000737:chemistry; D005954:Glucosephosphate Dehydrogenase / Q000737:chemistry; D064267:Intrinsically Disordered Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D007770:L-Lactate Dehydrogenase / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D018515:Plant Leaves / Q000737:chemistry; D010940:Plant Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D017510:Protein Folding; D020033:Protein Isoforms / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D055550:Protein Stability; D017433:Protein Structure, Secondary; D020543:Proteome / Q000737:chemistry; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D029681:Arabidopsis Proteins; D064267:Intrinsically Disordered Proteins; D008081:Liposomes; D010940:Plant Proteins; D020033:Protein Isoforms; D020543:Proteome; D011994:Recombinant Proteins; C066246:late embryogenesis abundant protein, plant; D007770:L-Lactate Dehydrogenase; D005954:Glucosephosphate Dehydrogenase; D051599:Glucose-1-Phosphate Adenylyltransferase
keywords: Drying; Enzyme stability; Fourier-transform infrared spectroscopy; Freezing; Intrinsically disordered protein; Late embryogenesis abundant protein