title: MpAsr encodes an intrinsically unstructured protein and enhances osmotic tolerance in transgenic Arabidopsis.
abstract: Abscisic acid-, stress- and ripening (ASR) -induced proteins are plant-specific proteins whose expression is up-regulated under abiotic stresses or during fruit ripening. In this study, we characterized an ASR protein from plantain to explore its physiological roles under osmotic stress. The expression pattern of MpAsr gene shows that MpAsr gene changed little at the mRNA level, while the MpASR protein accumulates under osmotic treatment. Through bioinformatic-based predictions, circular dichroism spectrometry, and proteolysis and heat-stability assays, we determined that the MpASR protein is an intrinsically unstructured protein in solution. We demonstrated that the hydrophilic MpASR protein could protect L: -lactate dehydrogenase (L: -LDH) from cold-induced aggregation. Furthermore, heterologous expression of MpAsr in Escherichia coli and Arabidopsis enhanced the tolerance of transformants to osmotic stress. Transgenic 35S::MpAsr Arabidopsis seeds had a higher germination frequency than wild-type seeds under unfavorable conditions. At the physiological level, 35S::MpAsr Arabidopsis showed increased soluble sugars and decreased cell membrane damage under osmotic stress. Thus, our results suggest that the MpASR protein may act as an osmoprotectant and water-retaining molecule to help cell adjustment to water deficit caused by osmotic stress.
authors.affiliation: The State Key Laboratory of Biocontrol and The Key Laboratory of Gene Engineering, Ministry of Education, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
authors.forename: Jin-Ran
authors.initials: JR
authors.lastname: Dai
authors.forename: Bing
authors.initials: B
authors.lastname: Liu
authors.forename: Dong-Ru
authors.initials: DR
authors.lastname: Feng
authors.forename: Hai-yan
authors.initials: HY
authors.lastname: Liu
authors.forename: Yan-ming
authors.initials: YM
authors.lastname: He
authors.forename: Kang-biao
authors.initials: KB
authors.lastname: Qi
authors.forename: Hong-Bin
authors.initials: HB
authors.lastname: Wang
authors.forename: Jin-Fa
authors.initials: JF
authors.lastname: Wang
mesh_terms: D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D018525:Germination; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008315:Malondialdehyde / Q000032:analysis; D008969:Molecular Sequence Data; D028521:Musa / Q000235:genetics* / Q000378:metabolism; D009995:Osmosis; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D055550:Protein Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012639:Seeds / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D013312:Stress, Physiological; D014867:Water / Q000378:metabolism; D015032:Zinc / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D014867:Water; D008315:Malondialdehyde; D007770:L-Lactate Dehydrogenase; D015032:Zinc