title: The role of hydrophobic amino acids of K-segments in the cryoprotection of lactate dehydrogenase by dehydrins.
abstract: Dehydrins, which are group 2 late embryogenesis abundant (LEA) proteins, accumulate in plants during the development of the embryo and exposure to abiotic stresses including low temperature. Dehydrins exhibit cryoprotection of freezing-sensitive enzymes, e.g. lactate dehydrogenase (LDH). Although it has been reported that K-segments conserved in dehydrins are related to their cryoprotection activity, it has not been determined which sequence features of the K-segments contribute to the cryoprotection. A cryoprotection assay using LDH indicated that 13 K-segments including 12 K-segments found in Arabidopsis dehydrins and a typical K-segment (TypK, EKKGIMEKIKEKLPG) derived from the K-segments of many plants showed similar cryoprotective activities. Mutation of the TypK sequence demonstrated that hydrophobic amino acids were clearly involved in preventing the cryoinactivation, cryoaggregation, and cryodenaturation of LDH. We propose that the cryoprotective activities of dehydrins may be made possible by the hydrophobic residues of the K-segments.
authors.affiliation: Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan. Electronic address: hara.masakazu@shizuoka.ac.jp.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Hara
authors.affiliation: Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Endo
authors.affiliation: Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Kamiya
authors.affiliation: Research Institute of Green Science and Technology, Shizuoka University, 836 Ohya, Shizuoka 422-8529, Japan.
authors.forename: Ayuko
authors.initials: A
authors.lastname: Kameyama
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry / Q000235:genetics*; D017360:Arabidopsis / Q000737:chemistry / Q000201:enzymology / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D003451:Cryoprotective Agents / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D007770:L-Lactate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D009154:Mutation
chemical_list: D000596:Amino Acids; D029681:Arabidopsis Proteins; D003451:Cryoprotective Agents; D007770:L-Lactate Dehydrogenase
keywords: Cryoprotection; Dehydrin; K-segment; Late embryogenesis abundant (LEA) proteins