A repeating 11-mer amino acid motif and plant desiccation.
Among the proteins that accumulate as plant seeds desiccate are several protein families that are composed principally of a tandemly repeated 11-mer amino acid motif. Proteins containing the same motif accumulate in the desiccating leaves of a desiccation-tolerant plant species. This motif is characterized by apolar residues in positions 1, 2, 5 and 9, and charged or amide residues in positions 3, 6, 7, 8 and 11. An alpha helical arrangement of the 11-mer repeating unit gives an amphiphilic helix whose hydrophobic stripe twists in a right-handed fashion around the helix. Should these proteins dimerize via binding of their hydrophobic faces, a right-handed coiled coil would be formed. Such a structure has not previously been observed. A conceivable function for these proteins in ion sequestration in the desiccated state is proposed.
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Department of Biochemistry, University of Georgia, Athens 30602.
D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D006360:Heat-Shock Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D010944:Plants / Q000235:genetics* / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid; D014867:Water / Q000378:metabolism*
D006360:Heat-Shock Proteins; D010940:Plant Proteins; C066246:late embryogenesis abundant protein, plant; D014867:Water