cDNA and gene sequences of wheat chloroplast sedoheptulose-1,7-bisphosphatase reveal homology with fructose-1,6-bisphosphatases.
The nucleotide sequence encoding the chloroplast enzyme, sedoheptulose-1,7-bisphosphatase [Sed(1,7)P2ase], was obtained from wheat cDNA and genomic clones. The transcribed region of the Sed(1,7)P2ase gene has eight exons (72-507 bp) and seven introns (85-626 bp) and encodes a precursor polypeptide of 393 amino acids. Comparison of the deduced amino acid sequence of Sed(1,7)P2ase with those of fructose-1,6-bisphosphatase [Fru(1,6)P2ase] enzymes from a variety of sources reveals 19% identity, rising to 42% if conservative changes are considered. Most importantly, the amino acid residues which form the active site of Fru(1,6)P2ase are highly conserved in the Sed(1,7)P2ase molecule, indicating a common catalytic mechanism. Interestingly, although the activities of both Sed(1,7)P2ase and chloroplast Fru(1,6)P2ase are modulated by light via the thioredoxin system, the amino acid sequence motif identified as having a role in this regulation in chloroplast Fru(1,6)P2ase is not found in the Sed(1,7)P2ase enzyme.
Raines
C A
CA
Biology Department, University of Essex, Colchester, England.
Lloyd
J C
JC
Willingham
N M
NM
Potts
S
S
Dyer
T A
TA
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D015152:Blotting, Northern; D002736:Chloroplasts / Q000201:enzymology*; D004247:DNA / Q000235:genetics*; D005091:Exons; D006597:Fructose-Bisphosphatase / Q000235:genetics* / Q000378:metabolism; D007438:Introns; D008969:Molecular Sequence Data; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000378:metabolism; D011061:Poly A / Q000235:genetics; D012313:RNA / Q000235:genetics; D012333:RNA, Messenger; D015183:Restriction Mapping; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D014908:Triticum / Q000201:enzymology*
D012333:RNA, Messenger; D011061:Poly A; D012313:RNA; D004247:DNA; D006597:Fructose-Bisphosphatase; D010744:Phosphoric Monoester Hydrolases; C022627:sedoheptulose-bisphosphatase