Identification in pea seed mitochondria of a late-embryogenesis abundant protein able to protect enzymes from drying.
Late-embryogenesis abundant (LEA) proteins are hydrophilic proteins that accumulate to a high level in desiccation-tolerant tissues and are thus prominent in seeds. They are expected to play a protective role during dehydration; however, functional evidence is scarce. We identified a LEA protein of group 3 (PsLEAm) that was localized within the matrix space of pea (Pisum sativum) seed mitochondria. PsLEAm revealed typical LEA features such as high hydrophilicity and repeated motifs, except for the N-terminal transit peptide. Most of the highly charged protein was predicted to fold into amphiphilic alpha-helixes. PsLEAm was expressed during late seed development and remained in the dry seed and throughout germination. Application of the stress hormone abscisic acid was found to reinduce the expression of PsLEAm transcripts during germination. PsLEAm could not be detected in vegetative tissues; however, its expression could be reinduced in leaves by severe water stress. The recombinant PsLEAm was shown to protect two mitochondrial matrix enzymes, fumarase and rhodanese, during drying in an in vitro assay. The overall results constitute, to our knowledge, the first characterization of a LEA protein in mitochondria and experimental evidence for a beneficial role of a LEA protein with respect to proteins during desiccation.
Grelet
Johann
J
Unité Mixte de Recherche 1191 Physiologie Moléculaire des Semences, Université d'Angers/INH/Institut National de la Recherche Agronomique, ARES, 49045 Angers cedex 01, France.
Benamar
Abdelilah
A
Teyssier
Emeline
E
Avelange-Macherel
Marie-Hélène
MH
Grunwald
Didier
D
Macherel
David
D
D000595:Amino Acid Sequence; D018506:Gene Expression Regulation, Plant; D008928:Mitochondria / Q000737:chemistry*; D008969:Molecular Sequence Data; D018532:Pisum sativum / Q000737:chemistry* / Q000502:physiology; D010940:Plant Proteins / Q000032:analysis / Q000502:physiology*; D012639:Seeds / Q000737:chemistry*; D014867:Water / Q000378:metabolism*
D010940:Plant Proteins; C066246:late embryogenesis abundant protein, plant; D014867:Water