A predicted N-terminal helical domain of a Group 1 LEA protein is required for protection of enzyme activity from drying.
Late embryogenesis abundant (LEA) proteins have been repeatedly implicated in the acquisition of desiccation tolerance in angiosperm seed embryos. However, the mechanism(s) by which protection occurs is not well understood. While the Group 1 LEA proteins are predicted to be largely unordered in solution, there is strong evidence that upon drying these proteins undergo a structural transition that leads to an increase in alpha-helical content. Several studies also suggest there is a direct interaction between Group 1 LEA proteins and other molecules in the cytoplasm that may be critical for the establishment of desiccation tolerance during embryo maturation. We have produced a recombinant Group 1 LEA protein and show that it is capable of protecting the enzyme lactate dehydrogenase from the deleterious effects of drying. We have also evaluated the ability of various altered recombinant Group 1 LEA proteins to protect in the same assay. Our results suggest that the highly conserved 20 amino acid Group 1 LEA signature motif is not required for protection in our in vitro assay. However, introduction of two juxtaposed proline residues into an N-terminal helical domain predicted to exist in the hydrated structure significantly compromises the ability of the recombinant protein to provide protection from drying. These results suggest that the N-terminal domain of Group 1 LEA proteins may be important for proper folding during dehydration.
Gilles
Gregory J
GJ
Department of Genetics and Biochemistry, 100 Jordan Hall, Clemson University, Clemson, SC 29634, USA.
Hines
Kelly M
KM
Manfre
Alicia J
AJ
Marcotte
William R
WR
D000595:Amino Acid Sequence; D001483:Base Sequence; D002942:Circular Dichroism; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D010957:Plasmids; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D014908:Triticum / Q000378:metabolism
D017931:DNA Primers; D010940:Plant Proteins; D011994:Recombinant Proteins; C066246:late embryogenesis abundant protein, plant